WO1980002219A1 - Dimensional sound producing apparatus and method - Google Patents

Dimensional sound producing apparatus and method Download PDF

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Publication number
WO1980002219A1
WO1980002219A1 PCT/US1980/000354 US8000354W WO8002219A1 WO 1980002219 A1 WO1980002219 A1 WO 1980002219A1 US 8000354 W US8000354 W US 8000354W WO 8002219 A1 WO8002219 A1 WO 8002219A1
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Prior art keywords
compensating
signal
time delay
component
main
Prior art date
Application number
PCT/US1980/000354
Other languages
French (fr)
Inventor
R Carver
Original Assignee
R Carver
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Publication date
Priority claimed from US06/027,473 external-priority patent/US4309570A/en
Priority claimed from US06/027,472 external-priority patent/US4218585A/en
Application filed by R Carver filed Critical R Carver
Publication of WO1980002219A1 publication Critical patent/WO1980002219A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S1/00—Two-channel systems
    • H04S1/002—Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution

Definitions

  • the present invention relates to a sound pro ⁇ ducing system particularly adapted to create a dimen ⁇ sionalized impression of the sound and to produce a recording capable of creating the dimensionalized impression of the sound.
  • a "diraension- * alized" effect can be obtained by transmitting differ ⁇ ent sound signals to the two speakers.
  • the speakers being positioned at two laterally spaced locations, and the listener being positioned rear- wardly of the speakers and facing toward a location between the speakers, a distinct sound that is trans ⁇ mitted only from the left speaker can be detected by the listener as coming from that source since the left and right ears of the. listener will detect a difference in intensity and also detect a phase shift so as to obtain the impression of the direction of the sound.
  • the direction of that source of sound can also be detected by the listener .
  • the sound can be expanded to the area encompassed by the two speakers .
  • the apparatus of the present invention is provi ⁇ ded to produce a dimensionalized audio signal to be used in conjunction with a pair of speakers where there is a playing area, where there are right and left speakers positioned at right and left speaker locations , and there is a listening area with a lis ⁇ tening location- At the listening area there are right " and left ear locations corresponding to right and left ear positions of a person's head which could be located at said listening locations and facing toward the playing area.
  • the apparatus comprises a left input means to receive a left stereo signal and a right input means to receive a right stereo signal.
  • left main transmitting means to trans ⁇ mit a left main signal component, corresponding and similar to the left stereo signal, to the left signal output means.
  • right main transmitting means to transmit a right main signal component, corresponding to and similar to the right stereo signal, to the right signal output means.
  • a left to right compensating means adapted to receive the left stereo signal to produce an inverted and delayed left to right compensating signal, corresponding to the left stereo signal, and to transmit said left to right compensating signal to the right signal output means.
  • right to left compensating means adapted to receive the right stereo signal to produce an in ⁇ verted and delayed right to left compensating signal corresponding to the right stereo signal, and to transmit the right to left compensating signal to the right signal output means.
  • the two compensating signals are delayed relative to corresponding main signal components by a time delay period within a . predetermined time delay range.
  • the left signal output means produces a left audio signal comprising the left main signal component and the right to left compensating signal.
  • the right signal output means produces a right audio signal comprising said right main signal component and said left to right compensating signal.
  • the result is that when the left audio signal drives the left speaker and the right audio signal drives the right speaker, the following occurs: a. there is a left audio output having a main left sound component and a right to left com ⁇ pensating sound component, said left audio output having a primary path component from . said left speaker to said left ear location, and a secondary path component from said left speaker to -said right ear location, b.
  • a right audio output having a main right sound component and a left to right compensating component, said right audio out ⁇ put having a primary path component from said right speaker to said right ear location, and a secondary pa * ch component from said right speaker location to said left ear location, c. the main left sound component reaches the left ear without being cancelled to a sub ⁇ stantial amount, d. the right main sound component reaches the right ear location without being cancelled to a substantial amount, e. the main left sound component travelling its secondary path to said right ear location is cancelled to a substantial amount by the left to right compensating sound component * travelling on the primary path from said right speaker to said right ear location, f.
  • time delay distance which is that distance that sound travels during the corresponding time delay period.
  • the apparatus is further characterized in that the time delay range for the compensating signals has a smaller time delay limit with a corresponding smaller time delay limit distance, and a larger time delay j-.lmi-c having a corresponding larger time delay distance limit.
  • the smaller and larger time delay distances encompass a range which includes an optimum time delay distance equal to a value obtained by mul- tiplying the sine of either listening angle times the ear spacing distance . .
  • each of the compensating signals have a plurality of compensating signal components, each having a different corresponding time delay distance component. Desirably at least one of these time delay distance components is smaller than the optimum time delay distance. Also, desirably at least one other of the time delay distance components is greater than the. optimum time delay distance.
  • At least some of the com ⁇ pensating signal components have decibel values lower than a decibel value of the corresponding main sound component.
  • at least one of the compensating signal components has a decibel value which varies with frequency, with lower frequencies of that com ⁇ pensating signal component having a higher decibel value than at higher frequencies of that compensating signal component .
  • the left and right main transmitting means com ⁇ prises, in the preferred form, frequency equalizer means.
  • Each of the frequency equalizers produces its main signal component with a higher decibel level for lower frequencies and a lower decibel level for higher frequencies .
  • This apparatus can also be used to produce re ⁇ cordings which can in turn produce dimensionalized sound.
  • a stereo re ⁇ cording device operatively connected to the left and right signal output means to receive the left and right audio signals.
  • the stereo recording device pro ⁇ Jerusalem a stereo sound recording with right and left information channels corresponding to the left and right audio signals.
  • the left signal output means produces the left information channel which comprises the left main signal component and said right to left com ⁇ pensating signal.
  • the right signal output means pro ⁇ Jerusalem the right * information channel which comprises the right main. signal component and the left to right compensating signal .
  • the left information channel drives the left speaker
  • the right information channel drives the right speaker .
  • left and right stereo signals are directed into left and right input means, respectively.
  • a left main signal component corresponding and similar to the left stereo signal, is transmitted to a left signal output means.
  • a right main signal component, corresponding to and similar to the right stereo signal is trans ⁇ mitted to a right signal output means.
  • the signal output means is used to produce sound through speaker means .
  • the signal output means are used to produce a sound recording which in turn can produce the desired sound components when played through a conventional stereo system.
  • the effect of the present invention is to produce a highly dimensionalized sound with a relatively high tolerance to head position and angle of the listener.
  • Other features will become apparent from the follow ⁇ ing detailed description.
  • Figure 1 is a schematic view illustrating the manner in which high quality stereo recordings are made
  • Figure 2 is a schematic view showing the manner in which a person receives sound waves-from the spea ⁇ kers of a typical audio system
  • Figure 3 is a schematic illustration of the appa ⁇ ratus of the present invention producing sound for a listener
  • FIG 4- is a schematic diagram of a switch in the apparatus of Figure 3;
  • Figure 5 is a table illustrating the magnitude of the compensating signal output components of the compensating signal
  • Figure 5 is a graph illustrating the intensity of the main signal component, as a function of fre ⁇ quency, produced by each of the frequency equalizers producing the main signal component;
  • Figure 7 is a schematic showing, similar to Figure.1 , to illustrate operating features of the present invention.
  • Figure.8 is a view of the listening area of Figure 5 to illustrate other operating features of the present invention.
  • Figure 9 is a view similar to Figure 8 , showing further operating features of the invention.
  • Figure 10 is a schematic illustration of the present invention producing signals for a stereo recorder. Best Mode For Carrying Out the Invention
  • FIG. 1 there are shown two microphones Ml and M2 spaced from each other and positioned in * front of an orchestra, indicated generally at 10, and comprising a plurality of orchestral components
  • micro ⁇ phone Ml may pick up the sound in the order of appro ⁇ ximately 1/100 of a second later than the microphone M2, since the sound must travel further to the micro ⁇ phone Ml .
  • the sound emanating from the instrument 12b would reach the .microphone Ml sooner and at a higher intensity than the sound from the instrument 12b would reach the microphone M2.
  • the microphone M2 At some intermediate location, e.g. at the location of the
  • the sound would reach the two micro ⁇ phones Ml and M2 at approximately the same time and same intensity.
  • the sound transmitted to the micro ⁇ phone Ml is used to produce a first signal which in turn is transmitted to the stereo recorder and repro ⁇ symbolized in the recording in a manner that when the re ⁇ cording is played, this signal, corresponding to the sound at microphone Ml , reproduces in One of the speakers a sound which is a substantial reproduction of the sound reaching the microphone Ml .
  • the sound reaching the microphone M2 is recorded in a manner that when the recording is played, the signal driving the other speaker corresponds to the sound transmitted to the microphone M2.
  • the speaker LS will first repro ⁇ duck this sound at the higher intensity level .
  • this sound would 'have first -and second components Ll and Lr reaching the left and right ears, Le and Re, respectively.
  • the two ears Le and Re would detect a difference in intensity of the two sound components Ll and Lr and also a phase shift of possibly 100 to * 300 microse ⁇ conds so that there would be a very definite sense of direction from the left speaker Ls .
  • the secondary sound component Lr is somehow eliminated so that in that first instant, only the left ear Le hears the sound which is travelling along the major sound com ⁇ ponent path Ll.
  • the instantaneous impression created on the person P is that the sound has emanated from a location which is more nearly immediately to the left of the person P.
  • the immediate impression is that the sound is totally out of the speaker area and is somewhere near the left side of the person.
  • the reproduction of these sounds in the two spea ⁇ kers LS and RS is timed somewhat closer together so that the left ear and the right ear Le and Re hear these two closer to the same intensity and somewhat closer together in a time frame.
  • the dimension ⁇ alized effect with regard to the sounds corresponding to those emanating from the instruments 12e and 12c can be presumed to be somewhat less than in the case of sounds emanating from the instruments 12b and 12f.
  • the overall effect of this is a rather startling creation of the impression that the sound is "totally dimensionalized” , in that the_ hearer somehow appears to be "within the sound" or in some manner surrounded by the various sources of the sound.
  • the appa ⁇ ratus can be so arranged that it isnot overly sensi ⁇ tive to the position or angle of the listener's head. For example, let it be assumed that the hearer is attracted more to a sound which appears to be coming in the direction from the left and the hearer turns his head toward that speaker. The dimensionalized effect created by the present invention is not sub ⁇ stantially diminished. Further, the hearer is able
  • Each of these frequency equalizers A(L) or A(R) is or may be any one of those well known in the prior art, and each functions to control the power of the output as a function of fre ⁇ quency.
  • the output from the frequency equalizer A(L) is directed to a summing junction C(L) and thence, through an amplifier (L) to the left speaker S(L).
  • the output from the right frequency equalizer A(R) is directed through a right summing junction C(R) to a right amplifier (R) to drive a right speaker S(R).
  • the left stereo input from L(IN) is directed to an inverting device B(LR) which in ⁇ verts the phase of the signal at L(IN) by 180 .
  • the output from the inverting device B(LR) is in turn transmitted through four channels to four time delay frequency equalizers, * designated bl(LR), b2(LR), b3(LR), b4(LR), respectively.
  • Each time delay frequen ⁇ cy equalizer, bl(LR)-b4.(LR) has two * functions , first, to change magnitude of the inverted signal as a func- tion of frequency, and secondly to delay the signal by a predetermined amount of time .
  • the collective output of the four time delay frequency equalizers bl(LR) through b4.TLR) produces a compensating signal which is transmitted to the right summing junction C(R).
  • This left-to-right com ⁇ pensating signal is superimposed over the main right stereo s_ignal output from the right frequency equal ⁇ izer A(R), and this combined signal in turn drives the right speaker S(R).
  • the output from the speaker S(R) is a sound pattern corresponding to the combined output from the summing junction C(R).
  • the right stereo input signal at R(IN) is transmitted through an inverting device B(RL) which inverts the signal by 180 .
  • the output from the inverting device B(RL) is transmitted along four channels to a second set of four time delay equalizers, designated bl(RL), b2(RL), b3(RL), and b4-(RL) .
  • bl(RL), b2(RL), b3(RL), and b4-(RL) the function of the se- cond set of time delay frequency equalizers bl(RL) through b4-(RL) is to provide a right to left compen ⁇ sating signal that is transmitted to the left summing junction C(L).
  • the compensating signal transmitted to the right summing junction C(L) is superimposed - over the main left stereo output from the frequency equalizer A(L) to provide a combined signal which drives the left speaker L(S).
  • each compensating signal is controlled by a related switch, Sw(L) or Sw(R), inter ⁇ posed between the input L(IN) or R(IN), respectively, and the related inverter B(RL) or B(LR), respective ⁇ ly.
  • This switch Sw(L) or Sw(R) is illustrated some ⁇ what schematically at Figure 4, where there are three voltage dividing resistors Rl , R2 and R3 in series.
  • the switching element ⁇ is open, the signal is delivered to the related inverter B(RL> or B(LR) at a lower intensity, i.e. about six decibels below the level of the signal at L(IN) or R(IN).
  • the intensity of the com ⁇ pensating signal is increased to about three decibels below the signal at L(IN) or R(IN).
  • the switches Sw(R) and Sw(L) act as "injection switches” to either increase or decrease the intensity of the compensa ⁇ ting signal to increase or decrease the dimension ⁇ alized effect of the sound produced.
  • each of the components indi- cated above are conventional components well-known in the electronics art, and each may be provided in any one of a number of conventional forms. For exam ⁇ ple, in a book entitled “Operational Amplifiers, De ⁇ sign and Applications", by Jerald G. Graeme, Gene E. Tobey and Lawrence P. Huelsman, published by.
  • the first set of time delay frequency equalizers bl(LR) through b4(LR) is to provide a delayed signal output, the intensity of which is modified as a function of fre ⁇ quency. The manner in which this is done is illustra- ted in the table of Figure 5. It can be seen in
  • the output from bl(LR) is delayedby a time increment tl or 110 microseconds.
  • the magnitude of the output from tl is equal to the input to the inverter B(LR) up until a frequency of 8 KHz is reached ' , after which the output is Zero.
  • the second time delay frequency equalizer b2(LR) With res ⁇ pect to the second time delay frequency equalizer b2(LR),- the time delay t2 is 180 microseconds, the magnitude of the output is similar to the unit bl(LR).
  • the third time delay frequency equalizer b3(LR) the period of delay t3 is 370 micro ⁇ seconds.
  • the time delay period t4 of- the fourth time delay frequency equalizer b4(LR) is ' .690 microseconds
  • component b3(LR) has ' for frequencies up to 200 Hz an output of 3.5 decibels above the input to the inverter B(LR).
  • the output is 3.5 decibels above the level of the input to the inverter B(RL) .
  • the two speakers S(R) - and S(L) and the person P are in what can be termed a "playing area", with the speakers S(L) and S(R) being at a forward location, and the person P being at a rear location.
  • the two speakers S(R) and S(L) are positioned along a base axis 20, and spaced from each other a ' predetermined spacing distance.
  • the person P is located at a "listening area 24", which is that area immedi ⁇ ately surrounding the head of the person P.
  • the head of the person P is located at a "listening location” which is a location on the longitudinal axis 22 at the ideal listening position for the apparatus .
  • the person P has a right ear Re and a left ear Le.
  • the sum total of this left-to-right compensating signal is made up of separate signal portions re— ceived in sequence at the input R(IN).
  • the invention is so arranged that the overall effect of the compen ⁇ sating signal, being superimposed on the main signal from the frequency equalizer A(L) is not sufficiently great to cause any noticeable degradation of the main signal from the frequency equalizer A(L).
  • this combined signal increment i.e. the left main signal with the superimposed right-to-left compensating signal
  • the sound emitted from the speaker can be consi ⁇ dered as travelling on two sound path components, one primary path component Ll which is'transmitted to the left ear Le of the person P, and a secondary path component Lr which is transmitted to the right
  • the left main sound on path component Ll reaches the left ear Le with no significant inter ⁇ ference, so that the left ear Le hears a substantial ⁇ ly undiminished left main sound resulting from the signal increment passing into the left stereophonic
  • That initial reaction would have some element of truth in that the present invention does in a sense eliminate or at least diminish some of the tradition- al functional features of stereophonic sound. How ⁇ ever, that analysis is incomplete since it does not take into consideration the nature of sounds produced by a stereophonic recording.
  • This left signal incre ⁇ ment results in an earlier main left sound emitted from the left speaker S(L) , and a delayed compensa ⁇ ting signal being emitted from the right speaker S(R) .
  • the compensating sound travelling the path Rr has a cancelling function. However, the compensating sound travelling the secondary path Rl to the left ear is not cancelled out. However, since the compen ⁇ sating sound from the right speaker S(R) is not only delayed relative to the corresponding main sound from the left speaker S(L), but also travels a longer secondary path Rl, the corresponding compensating from sound speaker S(R) reaches the left ear Le sub ⁇ stantially later than the main sound travelling the path Ll. It has been found that this does not cause any significant degradation of the main ⁇ sound compo- nent. (e) Operation of the Invention Relative to
  • right and left listening axes extending from the lis ⁇ tening location to the right and left speakers S(R) and S(L) respectively.
  • the right listening axis makes a right listening angle with the longitudinal axis, and in a like manner the left listening axis makes a left listening angle with the longitudinal axis .
  • the left and right ears of the listener are indicated at Le and Re respectively, and the "ear spacing dis ⁇ tance" is also indicated. For the purposes of this analysis , the ear spacing distance shall be presumed to be 7 inches.
  • Figure 8 shows the listening location and the right and left ear Re and Le on an enlarged scale.
  • the primary and secondary sound path components indicated at Rr, Rl , Lr and Ll . Since the two speakers are generally spaced from the listening location at a large distance, relative to the spacing distance of the two ears Re and L , for purposes of the present analysis, the left primary and secondary paths Ll and Lr can be considered to be parallel to one another, and the primary and secondary right paths Rr and Rl can also be considered to ' be parallel to one another.
  • time delay distance will * be used to denote an increment of distance over which sound will travel during a predetermined delay period.
  • the time delay distance would be approximately 1.3 inches.
  • This ideal time delay distance is illustra ⁇ ted ⁇ raphically at "x" in Figure 8 •
  • the sine value would be between 0.5 and 0.707.
  • the range of the ideal- time delay distance would be in the range of between 230 microseconds and 460 micro ⁇ seconds .
  • the left ear Le has moved closer to the left speaker S(L) by a distance of "z" which is only moderately less than the distance "y” .
  • the left ear Le has in effect moved laterally by an increment of distance indicated at "m” in Figure 8.
  • the 'change in the ideal time delay distance should be equal to twice the value 'm' times the sine of the listening angle.
  • Figure 9 is a representation quite similar to Figure 8, where "the person's right and left ears Re and Le are shown at the listening location. Let it be assumed that the person moves his head to the right , ' with no forward movement and no rotational movement. Four locations are shown for each ear. The left ear is shown at its ideal location, and then moved to the right by three increments, each increment .. " being equal to .one- quarter of the ear spacing distance. In like manner, the right ear is shown at its original position Re and also at three spaced locations to the right, each spacing being equal to one-quarter of the ear spacing distance.
  • the ideal time delay distance * With the left and right ears at the ideal position, at Le and Re, the ideal time delay distance *" remains at the value of the ear spacing distance times the sine of the listening angle.
  • the left ear simulta ⁇ neously moves further from the left speaker S(L) and closer to the right speaker S(R).
  • Each increment * of change is equal, to the distance increment of lateral travel times the sine of the listening angle.
  • the effect of these two increments ' is cumulative, so that the net change in the ideal time delay distance relative to the left ear is equal to two times the lateral movement of the left ear times the sine of the listening angle.
  • the left ear By the time the left ear reaches the location of the longitudinal axis (at Le(b)), ' the ear is qually distant from both speakers . Thus , the time delay distance to obtain sound cancellation has been reduced to zero . Further movement of the left ear to the location Le(c), indicates that there is actually a negative time delay distance to obtain cancellation. In other words, the cancelling sound from the right speaker S(R) would have to be emitted before the main left signal was emitted from the left speaker S(L) .
  • the ideal time delay distance would increase at the same rate that it would decrease for * the left ear.
  • the time-delay distance would be, respectively, one and one-quarter of the ideal time delay distance, one and one-half of the ideal time delay distance, and one and three-quarters of the ideal time delay distance.
  • the compensating signal is transmitted over a plurality of spaced time delay increments.
  • the selection of these time delay increments was obtained partly analyti ⁇ cally and partly empirically.
  • the time delay distance increments for the various time delay increments are given below: time delay • ⁇ zime delay increment distance incre;- (microseconds) ments (inches) tl 110 1.53 t2 180 2.34 t3 370 4.81 t4 690 8.97
  • the ear spacing distance is 7 inches, and that each of the listening angles is 45 .
  • the ideal time delay distance would be approximately five inches.
  • the compensating sound at the time delay increment t3 (which has a precise time delay distance of 4.81 inches) would be the primary cancelling sound.
  • the cancelling sound having time delay increments of first t2 , and then tl would come into play.
  • the effect of the cancelling sound having a time delay increment of t3 would still be effective as the right ear moves further from the longitudinal axis, but would be diminished somewhat.
  • time delay increments can be varied, and the amount of variation will depend to some extent on the relative. intensity of the main signal component and the compensating signal components .
  • the ranges are believed to be approximately as follows: • ⁇ time delay time ' distance delay range """ .. increment (inches) tl 1-3 t2 • 2-4 . t3 3-7 t4 6-12
  • each combined signal emitted from the summing junctions C(L) and C(R) is directed back through a time delay device D(L) or D(R) back to the input source L(IN) or R(IN).
  • the amount of time delay is 800 microseconds , which • is moderately longer than the longest time delay increment of the time delay frequency equalizers b4(RL) and b4(LR).
  • the effect of this is to direct the ., . total signal (the main signal plus the compensating signal), back through the system.
  • the total signal is not only directed back through the same summing junction, but is also directed through the crossover circuit to the opposite summing junction.
  • the reflected sounds should also be compensated for to some extent.
  • the stereo speakers are placed on the floor, close to the floor, or possibly in a corner. Accordingly, it is expected that sound will be reflected off the floor and/or walls and be directed to the hearer at a time delay in the order of possibly one millisecond, or so. It is believed that this feedback mechanism D(L) and D(R), being fed back through the system and delayed, at least partially compensate for this reflected sound.
  • FIG. 10 The recording apparatus of the present invention is illustrated in Figure 10.
  • L(IN) and R(IN) the signal inputs to these terminals L(IN)- and R(i;N) should be stereo signals, such as those produced at the microphones"Ml and M2 of Figure 1.
  • One method is to use the recording set-up as indicated in Figure 1, ' and attach the two spaced microphones Ml and M2 to respective input terminals L(IN) and R(IN).
  • the two terminals L(IN) and R(IN) receive stereo signals, where there are corresponding sound components in each signal, with time delays and intensity changes between the corresponding components of the signal.
  • An alternate method of providing the inputs to the terminals L(IN) and R(IN) is simply to take a stereo recording which is made according to the system of Figure 1, and play this recording on a stereo player. Then, instead"of directing, the signals produced by the player to speakers , these signals are directed to the input terminals L(IN) and R(IN). This method is indicated in broken lines in Figure 4-.
  • left and right signals are in turn trans ⁇ mitted directly from terminals L(IN) and R(IN) to left and right frequency equalizers, designated
  • Each of these frequency equalizers A(L) or A(R) is- or may be any one of those- well known in the prior ar , and each functions to control the power of the output as a function of frequency.
  • the output from the frequency equalizer A(L) is directed to a summing junction C(L) and thence to a stereo recorder.
  • the output from the right frequency equalizer A(R) is directed through a right summing junction.
  • C(R) to the _ stereo recorder.
  • the left stereo input from L(IN) is directed to an inverting device B(LR) which inverts the phase of the signal at L(IN) by 180 .
  • the output from the inverting device B(LR) is in turn transmitted through four channels to four time delay frequency equalizers, designated bl(LR), b2(LR), b3(LR) and b4-(LR), respectively.
  • Each time delay frequency equalizer, bl (LR)-b4-(LR) has two functions, first, to change magnitude of the inverted signal as a function of frequency, and secondly to delay the signal by a predetermined amount of .time.
  • the collective output of the four time delay frequency equalizers bl(LR) through b4-(LR) provides a compensating signal which is -transmitted to the right summing junction C(R).
  • This left-to-right stereo signal is superimposed over the main right stereo signal output from the right frequency equalizer A(R) , and this combined signal in turn is transmitted to the stereo recorder.
  • the right -stereo input signal at R(IN) is transmitted through an inverting device B(RL) which inverts the signal by 180 .
  • the output from the inverting device B(RL) is transmitted along four channels to a second set of four time delay equalizers, designated bl(RL), b2(RL), b3(RL), and b4(RL).
  • the function of the second set of time delay frequency equalizers bl(RL) through b4-(RL) is to provide a right to left compensating signal that is transmitted to the left summing junction C(L) .
  • the compensating signal transmitted to the left summing junction C(L) is superimposed over the main left stereo output from the frequency equalizer A(L) to provide a combined signal which also is transmitted to the stereo recorder.
  • the apparatus of Figure 10 is substantially similar to the apparatus of Figure 3, so the description of the apparatus of Figure 10 will not be carried further.”
  • FIG. 2 Let it be assumed that the sound recording made in the stereo recorder by the apparatus of Figure 10 is now placed upon a stereo player which in turn is connected to two speakers LS and RS .
  • the stereo player and the two speakers LS and RS can be a conventional player and speakers such as those well known in the prior art.
  • the player has the capability of taking one of the signals on the sound recording and transmitting this to one speaker LS to reproduce a sound relating to that first signal,, and to take the second signal and direct it to the other speaker RS to produce a second sound corresponding to that second signal.
  • the sounds produced by the speakers of Figure 2 are in this instance substantially the same as the sounds produced by the speakers of Figure 3, so no further explanation of these will be added.

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Abstract

Sound reproducing system having right and left speakers, (S(R) and S(L)), respectively, which produce right and left stereo sounds, respectively (Fig. 3). A right stereo signal in addition to driving the right speaker (S(R)), is inverted (B(RL)) and delayed (b1(RL) to b4(RL)) to produce a compensating signal which is transmitted to the left speaker (S(L)) to produce a delayed compensating sound pattern from the left speaker. The signal for the left speaker (S(L)) is inverted (B(LR)) and delayed (b1(LR) to b4(LR)) in a manner to produce a compensating sound pattern from the right speaker. The compensating sounds substantially cancel the main stereo sounds (R1 and Lr) travelling to a person"s ear (Re and Le) that is further from that speaker, to produce a dimensionalized effect where some of the sounds appear to be outside of the speaker area. In a second embodiment, the main stereo signals and the compensating signals are used to produce a recording (Fig. 10) which in turn produces the main stereo sounds and the compensating sounds to produce a dimensionalized effect.

Description

Description
Dimensional Sound Producing • Apparatus and Method
Technical Field The present invention relates to a sound pro¬ ducing system particularly adapted to create a dimen¬ sionalized impression of the sound and to produce a recording capable of creating the dimensionalized impression of the sound.
Background Art
In a typical stereophonic sound reproduction system, where there are two speakers, a "diraension- *alized" effect can be obtained by transmitting differ¬ ent sound signals to the two speakers. Thus, with the speakers being positioned at two laterally spaced locations, and the listener being positioned rear- wardly of the speakers and facing toward a location between the speakers, a distinct sound that is trans¬ mitted only from the left speaker can be detected by the listener as coming from that source since the left and right ears of the. listener will detect a difference in intensity and also detect a phase shift so as to obtain the impression of the direction of the sound. When another distinct sound is transmitted from the right speaker, the direction of that source of sound can also be detected by the listener . Thus , the sound can be expanded to the area encompassed by the two speakers .
There have been attempts in the prior art to give even greater dimension to the sound reproduction
"BUR£4 system, so that there is the impression that the sound is coming from areas totally outside of the more limi¬ ted area at and between the two speaker locations. While the applicant is not totally familiar with the operation of these systems, according to the appli¬ cant's present understanding, such systems require rather limited conditions of operation. For example, it is known that the prior art systems known to the applicant must be utilized in an environment where there is very little reflected sound, for example in an open space, or in a room where the walls are made of a highly sound absorbent material. Further, the systems which are known to the applicant are quite sensitive to the location of the hearer's head. Thus, if the person moves -his head from a precise listening position location, or rotates his head moderately toward one speaker or the other, a large part of the dimensionalized effect is lost. Thus, to the best knowledge of the applicant, these systems have remain- ed more in the category of laboratory curiosities , rather than a system which is practical for general use .
It is believed that the prior art systems discus¬ sed immediately above are operated on the basis of recognizing that sound emanating from various loca¬ tions both forwardly and rearwardly of a person' s head create different sound patterns relative to the person's ears. Thus, a sound emanating from a location in front of the person and 30 to the left would pro- duce distinctly different relative sound patterns • to the person's ears than a sound emanating directly from a location at the person's left. There would be a difference in intensity for the various fre¬ quencies, and also a different phase shift detected by the person's two ears. It is believed that this phenomenon is utilized to- tailer or control the sound emanating from the speakers to cause delicate adjust¬ ments in the phase shift and sound intensity at dif¬ ferent frequencies to produce the effect of greater dimensionalized sound. However, as indicated above, it is believed that the sensitivity of such systems to reflected sound and also head location have not made them practical for general use.
Also, there has been in the prior art recognition of the phenomenon called "cross talk" which in certain circumstances has the effect of degrading the quality of the sound transmitted from two spaced speakers . To describe this phenomenon briefly, the sound from* a right speaker reaches both the right and left ear of the person, but reaches the left ear at a slightly later time depending on the distance between the speakers, the listening angle, and the ear spacing of the listener (e.g. at a time ranging from zero to 900 microseconds) and at a somewhat lower intensity than the sound which reaches the' right ear.' The sound from the left speaker acts in somewhat the same way relative to the left and right ears. With similar sounds being emitted from both speakers something of the stereophonic effect is lost or at least dimi¬ nished by this phenomenon of cross talk. To the best knowledge of the applicant, the prior systems have attempted to alleviate the adverse effect of cross - talk by. providing compensating signals which combine with the cross talk signals to produce the proper phase shift.
It is an object of the present invention to provide a method and apparatus to produce a greater dimensionalized sound effect, which method and appa- ratus would be practical for general use , in that is is less sensitive to reflected sound and head location,
Disclosure of the Invention
The apparatus of the present invention is provi¬ ded to produce a dimensionalized audio signal to be used in conjunction with a pair of speakers where there is a playing area, where there are right and left speakers positioned at right and left speaker locations , and there is a listening area with a lis¬ tening location- At the listening area there are right "and left ear locations corresponding to right and left ear positions of a person's head which could be located at said listening locations and facing toward the playing area. ' The apparatus comprises a left input means to receive a left stereo signal and a right input means to receive a right stereo signal. There are left and right output means to produce audio signals for,- res¬ pectively, the left and right speakers.
There is a left main transmitting means to trans¬ mit a left main signal component, corresponding and similar to the left stereo signal, to the left signal output means. In like manner, there is a right main transmitting means to transmit a right main signal component, corresponding to and similar to the right stereo signal, to the right signal output means.
There is a left to right compensating means adapted to receive the left stereo signal to produce an inverted and delayed left to right compensating signal, corresponding to the left stereo signal, and to transmit said left to right compensating signal to the right signal output means. In like manner, there is right to left compensating means adapted to receive the right stereo signal to produce an in¬ verted and delayed right to left compensating signal corresponding to the right stereo signal, and to transmit the right to left compensating signal to the right signal output means. The two compensating signals are delayed relative to corresponding main signal components by a time delay period within a . predetermined time delay range.
Thus, the left signal output means produces a left audio signal comprising the left main signal component and the right to left compensating signal. The right signal output means produces a right audio signal comprising said right main signal component and said left to right compensating signal. The result is that when the left audio signal drives the left speaker and the right audio signal drives the right speaker, the following occurs: a. there is a left audio output having a main left sound component and a right to left com¬ pensating sound component, said left audio output having a primary path component from . said left speaker to said left ear location, and a secondary path component from said left speaker to -said right ear location, b. there is a right audio output having a main right sound component and a left to right compensating component, said right audio out¬ put having a primary path component from said right speaker to said right ear location, and a secondary pa*ch component from said right speaker location to said left ear location, c. the main left sound component reaches the left ear without being cancelled to a sub¬ stantial amount, d. the right main sound component reaches the right ear location without being cancelled to a substantial amount, e. the main left sound component travelling its secondary path to said right ear location is cancelled to a substantial amount by the left to right compensating sound component * travelling on the primary path from said right speaker to said right ear location, f. the main right sound component travelling ' on the secondary path from said right speaker to said left ear location is cancelled to a substantial amount by the right to left compensating sound component travelling from said left speaker along the left primary path to the left ear location. The result is that a person positioned so that the person's head is at the listening location facing along toward the transmitting area hears a dimen- • sionalized sound with apparent sound sources being outside of the transmitting area of the two speakers.
There is for each time delay period time delay distance, which is that distance that sound travels during the corresponding time delay period. The apparatus is further characterized in that the time delay range for the compensating signals has a smaller time delay limit with a corresponding smaller time delay limit distance, and a larger time delay j-.lmi-c having a corresponding larger time delay distance limit. The smaller and larger time delay distances encompass a range which includes an optimum time delay distance equal to a value obtained by mul- tiplying the sine of either listening angle times the ear spacing distance . .
Desirably, each of the compensating signals have a plurality of compensating signal components, each having a different corresponding time delay distance component. Desirably at least one of these time delay distance components is smaller than the optimum time delay distance. Also, desirably at least one other of the time delay distance components is greater than the. optimum time delay distance.
In the preferred form, at least some of the com¬ pensating signal components have decibel values lower than a decibel value of the corresponding main sound component. Also, at least one of the compensating signal components has a decibel value which varies with frequency, with lower frequencies of that com¬ pensating signal component having a higher decibel value than at higher frequencies of that compensating signal component . The left and right main transmitting means com¬ prises, in the preferred form, frequency equalizer means. Each of the frequency equalizers produces its main signal component with a higher decibel level for lower frequencies and a lower decibel level for higher frequencies .
This apparatus can also be used to produce re¬ cordings which can in turn produce dimensionalized sound. In that configuration there is a stereo re¬ cording device operatively connected to the left and right signal output means to receive the left and right audio signals. The stereo recording device pro¬ duces a stereo sound recording with right and left information channels corresponding to the left and right audio signals. Thus , the left signal output means produces the left information channel which comprises the left main signal component and said right to left com¬ pensating signal. The right signal output means pro¬ duces the right* information channel which comprises the right main. signal component and the left to right compensating signal . Thus , when the sound recording is played on a stereo player connected" to right and left speakers , the left information channel drives the left speaker, and the right information channel drives the right speaker .
In the method of the present invention, left and right stereo signals are directed into left and right input means, respectively. A left main signal component, corresponding and similar to the left stereo signal, is transmitted to a left signal output means. A right main signal component, corresponding to and similar to the right stereo signal, is trans¬ mitted to a right signal output means. There is produced from the left stereo signal an inverted and delayed left to right compensating signal, corresponding to the- left stereo signal. This is transmitted to the -right signal output means . There is also produced from the right stereo signal an inverted and delayed right to - left compensating signal, corresponding to the right stereo signal. This is transmitted to the left signal output means.
In one embodimen , the signal output means is used to produce sound through speaker means . In another embodiment the signal output means are used to produce a sound recording which in turn can produce the desired sound components when played through a conventional stereo system.
The effect of the present invention is to produce a highly dimensionalized sound with a relatively high tolerance to head position and angle of the listener. Other features will become apparent from the follow¬ ing detailed description.
Brief Description of the Drawings
Figure 1 is a schematic view illustrating the manner in which high quality stereo recordings are made;
Figure 2 is a schematic view showing the manner in which a person receives sound waves-from the spea¬ kers of a typical audio system;
Figure 3 is a schematic illustration of the appa¬ ratus of the present invention producing sound for a listener;
Figure 4- is a schematic diagram of a switch in the apparatus of Figure 3;
Figure 5 is a table illustrating the magnitude of the compensating signal output components of the compensating signal;
Figure 5 is a graph illustrating the intensity of the main signal component, as a function of fre¬ quency, produced by each of the frequency equalizers producing the main signal component;
Figure 7 is a schematic showing, similar to Figure.1 , to illustrate operating features of the present invention;
Figure.8 is a view of the listening area of Figure 5 to illustrate other operating features of the present invention;
Figure 9 is a view similar to Figure 8 , showing further operating features of the invention;
Figure 10 is a schematic illustration of the present invention producing signals for a stereo recorder. Best Mode For Carrying Out the Invention
To appreciate the novel features of the present invention, it is believed that a detailed description of the present invention should be preceded by a gene- ral analysis of the sound patterns which are utilized in stereophonic recording. This will be discussed by analyzing first how higher .quality stereophonic recordings are made, and reference is .made to Figure 1..for .this portion of the explanation. ir (a) Analysis of Stereophonic Recordings
In Figure 1 , there are shown two microphones Ml and M2 spaced from each other and positioned in * front of an orchestra, indicated generally at 10, and comprising a plurality of orchestral components
15 (i.e. musical instruments 12a through 12g) . Let it be assumed that the two microphones Ml and M2 are positioned relatively close to the orchestra and spaced from each other by moderately more than ten fee .
20 The sound from instrument 12f travels on a first shorter path 14 to microphone M2, and on a second longer path 16 to microphone Ml . Obviously the micro¬ phone M2 will record the sound from instrument' 12f at a higher intensity than will the microphone Ml.
25 Also, there will be a phase shift in that the micro¬ phone Ml may pick up the sound in the order of appro¬ ximately 1/100 of a second later than the microphone M2, since the sound must travel further to the micro¬ phone Ml .
30 In like manner, the sound emanating from the instrument 12b would reach the .microphone Ml sooner and at a higher intensity than the sound from the instrument 12b would reach the microphone M2. At some intermediate location, e.g. at the location of the
' instrument 12d, the sound would reach the two micro¬ phones Ml and M2 at approximately the same time and same intensity. The sound transmitted to the micro¬ phone Ml is used to produce a first signal which in turn is transmitted to the stereo recorder and repro¬ duced in the recording in a manner that when the re¬ cording is played, this signal, corresponding to the sound at microphone Ml , reproduces in One of the speakers a sound which is a substantial reproduction of the sound reaching the microphone Ml . In like man¬ ner, the sound reaching the microphone M2 is recorded in a manner that when the recording is played, the signal driving the other speaker corresponds to the sound transmitted to the microphone M2. Let us know discuss the situation when these two distinct sound signals are played on a recording and reproduced in a stereophonic system, with refer¬ ence being made to Figure 2. Let it be assumed that the signal produced at the microphone M2 is used in a manner to produce sound in the left speaker LS, while, the signal produced at the microphone IMI is used in the recording to produce a sound in the right speaker RS.
With regard to the sound produced by the instru- ment 12f of Figure 1 , the speaker LS will first repro¬ duce this sound at the higher intensity level . As indicated previously this sound would 'have first -and second components Ll and Lr reaching the left and right ears, Le and Re, respectively. At that instant, the two ears Le and Re would detect a difference in intensity of the two sound components Ll and Lr and also a phase shift of possibly 100 to * 300 microse¬ conds so that there would be a very definite sense of direction from the left speaker Ls . However, about l/lOOth of a second later,' essentially the same sound produced originally from the instrument 12f would be reproduced from the right speaker RS at a lower level of intensity, along the two components Rland Rr. If the sounds from the two speakers LS and Rs were of equal intensity and in phase, there would be no stereophonic effect. However, with the sound froπT'the left speaker LS" being of 'greater intensity" and different phase , there is something of the stereo¬ phonic effect, butthis is obscured to some extent by a very similar sound emanating from the right" spea¬ ker RS .
Consideration is now given to the sounds emana- ting from the centrally located instrument 12d. As indicated previously, since the distances from the instrument 12d to the two microphones Ml and M2 are substantially equal, the timing and intensity of the sounds at Ml and M2 are substantially the same. Thus, when the sound from the instrument 12d is reproduced in the two speakers LS and RS , the sounds from the two speakers LS and RS travelling the main path components Ll and Rr reach the left and right ears Le and Re simultaneously. The two se- condary sound components , ' Lr and Rl , reach the two ears Le and Re simultaneously, but possibly 100 to 300 microsenconds later than the main sound compo¬ nents Ll and Rr.
Let it now be assumed that with respect to the reproduced sound corresponding to that produced from the instrument 12d, the two secondary sound compo¬ nents Lr and Rl are both cancelled, so that the Le hears only a left main sound component Ll and the right ear Rr hears only the right main component Rr . With the "two ears hearing substantially the same sound at the same intensity, there will be the impres¬ sion that the sound is coming from a central location immediately forward of the person P.
(b) Theory of the Present Invention To proceed now to a discussion of the present invention, the present invention is based upon the theory that two corresponding sounds (i.e. sounds . .- which emanate from the same originating instrument in the making of the initial recording) which corres¬ ponding sounds are recorded in sequence (i.e. this occuring when the instrument is closer to one record- • ing microphone than the other) can be utilized to produce a dimensionalized effect much broader than the area occupied by the speakers. In fact, these sounds can be utilized to produce a nearly total dimensionalized effect where it. appears that the music is in a sense "surrounding" the listener. While the theory which is to be proposed below is believed to account properly for the phenomenon of the present invention, it should be stressed that regardless of the accuracy or validity of the follow¬ ing theory, it has been found., that the present inven- tion is able to produce this nearly total dimension¬ alized effect of the sound.
To proceed further with the presentation of the theory of the present invention, and with further reference to Figure 2, let it be assumed that two sounds corresponding to those emanating from the in¬ strument 12f are now reproduced, in the two speakers LS and RS. With the sound picked up from the micro¬ phone M2 being reproduced through the speaker LS , the sound of the instrument 12f is transmitted at an earlier time along the two path components Ll and Lr. As indicated previously, in the first instant where the two sound components Ll and Lr reach the ears Le and Re, there is something of a dimension¬ alized effect in that the hearer distinctly has the impression that the sound is emanating from the speaker LS.
However, let it be assumed that the secondary sound component Lr is somehow eliminated so that in that first instant, only the left ear Le hears the sound which is travelling along the major sound com¬ ponent path Ll.. With the right ear Re hearing nothing of that sound, the instantaneous impression created on the person P is that the sound has emanated from a location which is more nearly immediately to the left of the person P. Thus, the immediate impression is that the sound is totally out of the speaker area and is somewhere near the left side of the person.
About a hundredth of a second later, let it fur¬ ther be assumed that the reproduced sound correspond- ing to that of instrument 12f is now emitted from the right speaker RS. Let it further be assumed that the secondary sound componen _R1 is eliminated so that only, the right ear Re hears the sound emanating from the speaker Rs. The impression is that there is a second instrument 12f positioned- in some area immediately to the right of the person, which also is outside the speaker area.
Let us no .give consideration to the sound that is reproduced which corresponds to the sound emana- ting from the instrument 12d. With the two secondary path components Lr and Rl being totally eliminated, and with the sound being emitted from the speakers LS and RS at substantially the same time and at sub- stantially the same intensity, there is the very clear impression that the "sound corresponding to that emanating from the instrument 12d is from a source immediately forward of the person. With regard to sounds emanating from the instruments 12c and 12e, since the difference in distance from these instru¬ ments to the microphones Ml and M2 is somewhat less, the time delay and difference in intensity with which these' sounds are recorded are somewhat less than in the case of the instruments 12b and 12f. Consequent¬ ly, the reproduction of these sounds in the two spea¬ kers LS and RS is timed somewhat closer together so that the left ear and the right ear Le and Re hear these two closer to the same intensity and somewhat closer together in a time frame. Thus, the dimension¬ alized effect with regard to the sounds corresponding to those emanating from the instruments 12e and 12c can be presumed to be somewhat less than in the case of sounds emanating from the instruments 12b and 12f. The overall effect of this is a rather startling creation of the impression that the sound is "totally dimensionalized" , in that the_ hearer somehow appears to be "within the sound" or in some manner surrounded by the various sources of the sound. Further, it has been found that in the present invention, the appa¬ ratus can be so arranged that it isnot overly sensi¬ tive to the position or angle of the listener's head. For example, let it be assumed that the hearer is attracted more to a sound which appears to be coming in the direction from the left and the hearer turns his head toward that speaker. The dimensionalized effect created by the present invention is not sub¬ stantially diminished. Further, the hearer is able
' E to shift his head moderately from side to side, with¬ out the dimensionalized effect being substantially diminished. When the hearer moves his head a further distance to the side (e.g. a foot or so), the dimen- sionalized effect is diminished, but not totally era¬ dicated. Thus, the person is able to sense this and move his head back to the ideal listening area, and continue to have comfortable angular movement of the head and moderate side to side movement while still enjoying the dimensionalized effect of the apparatus. (c) Apparatus of a First Embodiment of The Pre-_- sent Invention The apparatus of the present invention is illus¬ trated in Figure 3. There are left and right stereo signals entering at terminal L(IN) and R(IN), respec¬ tively, and these are in turn transmitted directly to left and right frequency equalizers, designated A(L) and A(R)*, respectively. Each of these frequency equalizers A(L) or A(R) is or may be any one of those well known in the prior art, and each functions to control the power of the output as a function of fre¬ quency. The output from the frequency equalizer A(L) is directed to a summing junction C(L) and thence, through an amplifier (L) to the left speaker S(L). in like manner, the output from the right frequency equalizer A(R) is directed through a right summing junction C(R) to a right amplifier (R) to drive a right speaker S(R).
Additionally, the left stereo input from L(IN) is directed to an inverting device B(LR) which in¬ verts the phase of the signal at L(IN) by 180 . The output from the inverting device B(LR) is in turn transmitted through four channels to four time delay frequency equalizers,* designated bl(LR), b2(LR), b3(LR), b4(LR), respectively. Each time delay frequen¬ cy equalizer, bl(LR)-b4.(LR) has two* functions , first, to change magnitude of the inverted signal as a func- tion of frequency, and secondly to delay the signal by a predetermined amount of time .
The collective output of the four time delay frequency equalizers bl(LR) through b4.TLR) produces a compensating signal which is transmitted to the right summing junction C(R). This left-to-right com¬ pensating signal is superimposed over the main right stereo s_ignal output from the right frequency equal¬ izer A(R), and this combined signal in turn drives the right speaker S(R). Thus the output from the speaker S(R) is a sound pattern corresponding to the combined output from the summing junction C(R).
In like manner, the right stereo input signal at R(IN) is transmitted through an inverting device B(RL) which inverts the signal by 180 . The output from the inverting device B(RL) is transmitted along four channels to a second set of four time delay equalizers, designated bl(RL), b2(RL), b3(RL), and b4-(RL) . As with the other time delay frequency equal¬ izers bl(LR) through b4-(RL), 'the function of the se- cond set of time delay frequency equalizers bl(RL) through b4-(RL) is to provide a right to left compen¬ sating signal that is transmitted to the left summing junction C(L). The compensating signal transmitted to the right summing junction C(L) is superimposed - over the main left stereo output from the frequency equalizer A(L) to provide a combined signal which drives the left speaker L(S).
The- intensity of each compensating signal is controlled by a related switch, Sw(L) or Sw(R), inter¬ posed between the input L(IN) or R(IN), respectively, and the related inverter B(RL) or B(LR), respective¬ ly. This switch Sw(L) or Sw(R) is illustrated some¬ what schematically at Figure 4, where there are three voltage dividing resistors Rl , R2 and R3 in series. When the switching element Ξ is open, the signal is delivered to the related inverter B(RL> or B(LR) at a lower intensity, i.e. about six decibels below the level of the signal at L(IN) or R(IN). When -the switch element E is closed, the intensity of the com¬ pensating signal is increased to about three decibels below the signal at L(IN) or R(IN). Thus the switches Sw(R) and Sw(L) act as "injection switches" to either increase or decrease the intensity of the compensa¬ ting signal to increase or decrease the dimension¬ alized effect of the sound produced.
Additionally, the output from the left summing junction C(L) is fed back through a left time delay device D(L) back to the left input junction L(IN). In like manner, the output from the right summing junction C(R) is fed back through- a right time delay means D(R) to the right input terminal R(IN). It should be understood that each of the components indi- cated above are conventional components well-known in the electronics art, and each may be provided in any one of a number of conventional forms. For exam¬ ple, in a book entitled "Operational Amplifiers, De¬ sign and Applications", by Jerald G. Graeme, Gene E. Tobey and Lawrence P. Huelsman, published by. McGraw-Hill Book Company, copyrighted 1971, such fre¬ quency equalizers are discussed in Chapter 5, enti¬ tled "Phase Compensation." Also such devices are des¬ cribed in a book, entitled "Linear Applications Hand- book" , sold by Radio Shack, and identified by Cat. No. 52-1373, particularly on page AN 64-9. Accord¬ ingly, a detailed description of each of these compo¬ nents is not included herein. As indicated previously herein, the first set of time delay frequency equalizers bl(LR) through b4(LR) is to provide a delayed signal output, the intensity of which is modified as a function of fre¬ quency. The manner in which this is done is illustra- ted in the table of Figure 5. It can be seen in
Figure 5 that the output from bl(LR) is delayedby a time increment tl or 110 microseconds. Also, the magnitude of the output from tl is equal to the input to the inverter B(LR) up until a frequency of 8 KHz is reached', after which the output is Zero. With res¬ pect to the second time delay frequency equalizer b2(LR),- the time delay t2 is 180 microseconds, the magnitude of the output is similar to the unit bl(LR). With regard to the third time delay frequency equalizer b3(LR), the period of delay t3 is 370 micro¬ seconds. The time delay period t4 of- the fourth time delay frequency equalizer b4(LR) is '.690 microseconds With regard to the magnitude of. the output of these two components, component b3(LR) has' for frequencies up to 200 Hz an output of 3.5 decibels above the input to the inverter B(LR). For the fourth time de¬ lay frequency equalizer b4(LR), for frequencies up to 400 Hz, the output is 3.5 decibels above the level of the input to the inverter B(RL) . For each of the components b3(LR) and b4(LR), after the intial plus 3.5 decibel output the output returns to a level equal to the input to inverter B(LR) until the fre¬ quency of 8 KHz is reached, after which the output
- drops to Zero . The action of the second set of time delay frequency equalizers bl(RL) through b4(RL) is identical to the first set, so the table of Figure 5 is intended to apply to the second set as well . It has been found that the. performance of the system of the present invention can be enhanced by controlling the intensity of the left main signal and right main signal as a function of* frequency. The manner in which this is done is illustrated by the graph of Figure 6, where the intensity of the sound emitted from each frequency equalizer A(R) and A(L) is plotted against frequency. It can be seen that the intensity of the sound produced is at a maxi¬ mum at 20 Hz, where it is 6 decibels above the incom- ing signal at L(IN) or R(IN). Then it declines at a substantially constant rate to a level at 400 Hz,, where there is no amplification of the signal. This intensity remains constant until it approaches the 4 KHz range where the intensity of the sound declines to minus 8 decibels below the incoming signal level, after which sound level climbs back up to the ordi¬ nary level, and remains at this"level until it reaches the 20 KHz range, (d) General Operation of the Present Invention To describe the operation of the present inven¬ tion let us now place a person P at a location rear- wardly of, and equally distant from, the -two speakers S(L) and S(R). To establish a proper frame of refer¬ ence, let it be assumed that the two speakers S(R) - and S(L) and the person P are in what can be termed a "playing area", with the speakers S(L) and S(R) being at a forward location, and the person P being at a rear location. The two speakers S(R) and S(L) are positioned along a base axis 20, and spaced from each other a' predetermined spacing distance. There is a longitudinal axis 22 perpendicular to the base axis 20 and equally distant from the locations of the speakers S(R) and S(L) . The person P is located at a "listening area 24", which is that area immedi¬ ately surrounding the head of the person P. The head of the person P is located at a "listening location" which is a location on the longitudinal axis 22 at the ideal listening position for the apparatus . The person P has a right ear Re and a left ear Le.
To describe the operation of the present inven¬ tion, let us examine first a very short time incre¬ ment of an audio signal which enters the left stereo input L(IN). This increment of sound is directed imme¬ diately to the left frequency equalizer A(L), the output of which is called the "left main signal.", which is directed to the summing junction C(L). At the summing junction C(L) there is also an increment of sound which originated from the righ input R(IN) and passed through the inverting device B(RL) and through the four time delay frequency equalizers, . bl(RL) .through b4-(RL) , to the summing junction C(L). This additional sound increment can be termed a"left- to-right compensating signal". Since the time delay for .each of the four time delay frequency equalizers bl(RL) through b4(RL) are different from one another, the sum total of this left-to-right compensating signal is made up of separate signal portions re— ceived in sequence at the input R(IN). The invention is so arranged that the overall effect of the compen¬ sating signal, being superimposed on the main signal from the frequency equalizer A(L) is not sufficiently great to cause any noticeable degradation of the main signal from the frequency equalizer A(L). When this combined signal increment (i.e. the left main signal with the superimposed right-to-left compensating signal) passes from the summing junction C(L) to the left speaker S(L), for purposes of analy-
5 sis the sound emitted from the speaker can be consi¬ dered as travelling on two sound path components, one primary path component Ll which is'transmitted to the left ear Le of the person P, and a secondary path component Lr which is transmitted to the right
10 ear Re. The left main sound on path component Ll reaches the left ear Le with no significant inter¬ ference, so that the left ear Le hears a substantial¬ ly undiminished left main sound resulting from the signal increment passing into the left stereophonic
15 input L(IN) .
However, this is not the case with the main left sound on the secondary path component Lr. It will be noted that the secondary path component Lr to the right ear Re is moderately longer than the primary
20. path component Ll . The* main left sound travelling the secondary path Lr is partially cancelled by the . sound originating from a left-to-right compensating signal which originates from the left stereophonic input L(IN) crossing over to the "right summing junc-
25 tion CR .by passing first through the inverter B(RL) through b4-(LR) .- The left-to-right compensating signal sound creates a compensation sound at the right speaker S(R) which is superimposed over the sound created by the main right signal delivered to the
30 right speaker S(R) . The sound from the speaker S(R) travels over a right primary path component Rr and over a secondary path component Rl . With the path componen Rr being shorter- than the secondary path Lr, the left-to-right* compensating sound is delayed to the extent that the left-to-right compensating sound reaches the right ear Re at approximately the same time as does the left corresponding main sound increment travelling along the secondary path compo¬ nent Lr. Since the compensating sound is 180 out of phase by reason of the inverter B(LR),- the' compen¬ sating sound at least partially cancels out the main left sound increment travelling the secondary path Lr. The net effect is that the left ear Le hears the left main sound increment substantially undiminished, while the right ear Re hears the left main sound in¬ crement very little or at a substantially diminished level.
With regard to the' right-to-left compensating signal which originates in.the right input R(IN), and is transmitted to the left speaker S(L), it was stated earlier that this signal is superimposed on the left main signal L(IN) which is transmitted from the frequency equalizer A(L) to the left speaker. However,, when the superimposed portion of the compen¬ sating sound travels from the,,left speaker S(L) along the primary path Ll to the left ear,' shortly before a corresponding right main sound is emitted from the right speaker S(R) and travels the secondary path Rl to the left ear Le. The compensating sound incre¬ ment travelling the path of Ll and the right primary sound emanating from the right speaker Ls and travel- ling component path Rl substantially cancel each other out at the left ear Le.
From the above description, it can be readily appreciated that the sound emanating from the left speaker S(L) is heard essentially by the left ear
-BU EAU Le only, while the sound emanating from the right speaker Rs is heard essentially only by the right ear Re. Without the benefit of the analysis accompany¬ ing the present invention, it is believed that the initial reaction' of a person first viewing the mode of operation of the present invention would come to the conclusion that the present invention is destroy¬ ing, some of the stereophonic effect obtained -by the two speakers . In other words , one' could argue that since a single sound emanating from the left speaker Ls would reach only the left ear Le and not the' right ear Re, the left and right ears could not make the differentiation in intensity and phase shift of the same sound travelling different paths to the two ears, and thus lose a valuable sensation of direction of source, which is part of the stereophonic effect. That initial reaction would have some element of truth in that the present invention does in a sense eliminate or at least diminish some of the tradition- al functional features of stereophonic sound. How¬ ever, that analysis is incomplete since it does not take into consideration the nature of sounds produced by a stereophonic recording.
To turn our attention briefly back to the discus- sion under the heading "Theory of the Present Inven¬ tion", -consideration was given to the effect of elimi¬ nating sound which travels along the two secondary paths Lr and Rl . This was discussed with reference to reproducing the sounds that are recorded in a ste- reophonic system such as that shown in Figure 3. A review of that discussion indicates that the sounds which are recorded with a substantial time delay (such as those emanating from the instrument I2f of Figure 3) produce a distinctly different impression to the hearer.when the sound along paths Lr and Rl are substantially eliminated.. Some of the sounds seem to move out of the transmitting area of the two speakers to in a sense "surround" the hearer. Other sounds appear to originate from the transmitting area between the- speakers. 'Ye 'other sounds give an inter¬ mediate impression of being "somewhere in between". Since this -was discussed in more detail in the pre¬ vious section entitled "Theory of the Present Inven¬ tion" , those remarks will not be repeated herein. To apply this theory to the actual operation of the present invention, there is not in the present invention a total elimination of the sounds travel¬ ling along the secondary paths Rl and Lr. For exam¬ ple, consider again the signal increment which enters the left input terminal L(IN). This left signal incre¬ ment results in an earlier main left sound emitted from the left speaker S(L) , and a delayed compensa¬ ting signal being emitted from the right speaker S(R) . The compensating sound travelling the path Rr has a cancelling function. However, the compensating sound travelling the secondary path Rl to the left ear is not cancelled out. However, since the compen¬ sating sound from the right speaker S(R) is not only delayed relative to the corresponding main sound from the left speaker S(L), but also travels a longer secondary path Rl, the corresponding compensating from sound speaker S(R) reaches the left ear Le sub¬ stantially later than the main sound travelling the path Ll. It has been found that this does not cause any significant degradation of the main ■sound compo- nent. (e) Operation of the Invention Relative to
Head Location and Angle It was indicated earlier herein 'that the present inventions can operate effectively even in circum- stances where the person rotates his head in one di¬ rection or the other, or shifts his head laterally to a moderate extent. To explain this particular facet of the vpresent invention, reference is made to Figure 7. in Figure 7 the right and left' speakers S(L) and S(R), respectively, and the listening loca¬ tion are indicated schematically. As described pre¬ viously, there is the base axis on which the two speakers S(L) and S(R) are located, and the longi¬ tudinal axis, which is perpendicular to the base axis and bisects the base axis. Additionally, there are right and left listening axes extending from the lis¬ tening location to the right and left speakers S(R) and S(L) respectively. The right listening axis makes a right listening angle with the longitudinal axis, and in a like manner the left listening axis makes a left listening angle with the longitudinal axis . The left and right ears of the listener are indicated at Le and Re respectively, and the "ear spacing dis¬ tance" is also indicated. For the purposes of this analysis , the ear spacing distance shall be presumed to be 7 inches.
Reference is now made to Figure 8 which shows the listening location and the right and left ear Re and Le on an enlarged scale. In addition to showing the longitudinal axis, the right and le t listening axes , and the right and left listening angles, also shown are the primary and secondary sound path components, indicated at Rr, Rl , Lr and Ll . Since the two speakers are generally spaced from the listening location at a large distance, relative to the spacing distance of the two ears Re and L , for purposes of the present analysis, the left primary and secondary paths Ll and Lr can be considered to be parallel to one another, and the primary and secondary right paths Rr and Rl can also be considered to 'be parallel to one another.
In the following analysis, the term "time delay distance" will* be used to denote an increment of distance over which sound will travel during a predetermined delay period. Thus, with sound travelling approximately 1080 feet per second (depending upon the ambient temperature), for a time delay of 100 microseconds, the time delay distance would be approximately 1.3 inches. With a person's head positioned exactly at the listening location, and with the person facing parallel to the longitudinal axis , to obtain ideal signal cancellation in the present invention, there should be a time delay distance equal to a value obtained by multiplying the sine of the listening angle times the ear spacing distance . This ideal time delay distance is illustra¬ ted σraphically at "x" in Figure 8 • On the assumption that the two speakers would be placed so that the two listening angles ' would be between 30 to 4-5 , the sine value would be between 0.5 and 0.707. On the assumption that the ear spacing distances between 6 and 8 inches , the range of the ideal- time delay distance would be in the range of between 230 microseconds and 460 micro¬ seconds .
Let us first give consideration to movement of the person ' s head forwardly and rearwardly about the longitudinal axis. Since the speakers S(L) and S(R) are generally placed a substantial distance from -the listener, ' elative to the ear spacing distance, it becomes readily apparent that limited forward and rearward movement of the person's head (up to several feet) would have very little change in the listening angle. Accordingly, there would be very little change in the value of the ideal time delay distance. Thus, the fore and aft movement of the person's head would have substantially little effect on the present invention.
Let it now be assumed that the hearer rotates his head to the extent that the hearer is* facing directly along the right listening axis toward the right speaker. The location of the left and right ears in this position are. indicated at Le1 and Re' . The precise point relative to the person's ears about which the turning .takes place will vary moderately from person to person, but in general it is reasonable to assume that this point of turning takes place at a point directly between the person's ears Le and Re. Thus, with further reference to Figure 8, it can be seen that the left' ear Le has moved closer to the right speaker by a distance "y" which is equal to one-half the ideal time delay distance "x" . Also, the left ear Le has moved closer to the left speaker S(L) by a distance of "z" which is only moderately less than the distance "y" . Further analysis indicates that when the ear Le moves from .its initial position to the turned position Le' ,the left ear Le has in effect moved laterally by an increment of distance indicated at "m" in Figure 8. With the ear in the position Le1 , to obtain ideal cancellation, the 'change in the ideal time delay distance should be equal to twice the value 'm' times the sine of the listening angle.
From the above analysis, it becomes apparent why the angular movement of the person's head about the listening location has little degrading effect in the operation of the present invention. In effect, an angular movement of, for example, up to 30 , causes a relatively greater forward movement and a relatively small lateral movement. As indicated previously, the system of the present invention is relatively insensitive to forward and rearward movement of the person' s head about the listening location". Thus , the only effect • really to be considered with regard to angular movement of the person's head is the limited lateral movement toward or away from the longitudinal axis which would actually change the time delay distance.
Consideration is now given to the effect that lateral movement (i.e. movement perpendicular to the longitudinal axis) would have on the time - delay distance. Reference is made to Figure 9, which is a representation quite similar to Figure 8, where "the person's right and left ears Re and Le are shown at the listening location. Let it be assumed that the person moves his head to the right , ' with no forward movement and no rotational movement. Four locations are shown for each ear. The left ear is shown at its ideal location, and then moved to the right by three increments, each increment .."being equal to .one- quarter of the ear spacing distance. In like manner, the right ear is shown at its original position Re and also at three spaced locations to the right, each spacing being equal to one-quarter of the ear spacing distance.
With the left and right ears at the ideal position, at Le and Re, the ideal time delay distance*" remains at the value of the ear spacing distance times the sine of the listening angle. When the left ear has moved to the right a distance equal to one-quarter of the ear spacing distance (i.e. to the location Le(a)), the left ear simulta¬ neously moves further from the left speaker S(L) and closer to the right speaker S(R). Each increment* of change is equal, to the distance increment of lateral travel times the sine of the listening angle. The effect of these two increments ' is cumulative, so that the net change in the ideal time delay distance relative to the left ear is equal to two times the lateral movement of the left ear times the sine of the listening angle. By the time the left ear reaches the location of the longitudinal axis (at Le(b)),' the ear is qually distant from both speakers . Thus , the time delay distance to obtain sound cancellation has been reduced to zero . Further movement of the left ear to the location Le(c), indicates that there is actually a negative time delay distance to obtain cancellation. In other words, the cancelling sound from the right speaker S(R) would have to be emitted before the main left signal was emitted from the left speaker S(L) .
With regard to the right ear Re, it becomes apparent that for each incremental movement to ' the right, the ideal time delay distance would increase at the same rate that it would decrease for* the left ear. Thus, at locations Re(a), Re(b) and Re(c), the time-delay distance would be, respectively, one and one-quarter of the ideal time delay distance, one and one-half of the ideal time delay distance, and one and three-quarters of the ideal time delay distance.
In the present invention, the compensating signal is transmitted over a plurality of spaced time delay increments. The selection of these time delay increments was obtained partly analyti¬ cally and partly empirically. The time delay distance increments for the various time delay increments are given below: time delay •{zime delay increment distance incre;- (microseconds) ments (inches) tl 110 1.53 t2 180 2.34 t3 370 4.81 t4 690 8.97 With further reference to Figure 8, let it be assumed that the ear spacing distance is 7 inches, and that each of the listening angles is 45 . Thus,, the ideal time delay distance would be approximately five inches. With the person's head being centrally located on the longitudinal axis , it can be seen that the compensating sound at the time delay increment t3 (which has a precise time delay distance of 4.81 inches) would be the primary cancelling sound. As the person moves his head laterally to the right, for the left ear, which is moving closer to the longitudinal axis and thus requires a shorter time delay incre¬ ment, the cancelling sound having time delay increments of first t2 , and then tl , would come into play. However, for the right ear, the effect of the cancelling sound having a time delay increment of t3 would still be effective as the right ear moves further from the longitudinal axis, but would be diminished somewhat. Thus, it can be appreciated that, with further reference to Figure 8 , when the person reaches the position indicated at Le(a) and Re(a), the cancellation phenomenon is still effective. With regard to the sensitivity of the compen¬ sating signal to position, it should be kept in mind that a sound having a fundamental frequency of "middle C" (i.e. 254- cycles per second) has a fundamental wave length of nearly four feet. Even for a sound of 1,000 cycles per second, the wave length is about a foot. Thus, there can still be substantial sound cancellation even where the. departures from the ideal time delay distance are in the order of several inches or more .
Therefore, even when the person reaches the position of the ears being at Le(b) and Re(b), there is still a substantial cancelling effect, since the cancelling sound waves are reasonably tolerant to moderate phase shifts . When the person' s head is moved yet further to the right , it becomes apparent that the cancellation phenomenon at the left ear Le is further diminished, and there is yet a fair amount of the cancellation phenomenon at the right ear, due to the compensating sounds that have time delay increments of t3 and t . For example, the cancellation sound with the time increment t4. would be fully effective when the person has moved his head nearly 5-1/2 inches from the longitudinal axis laterally to the right. When the person moves his head a substantial distance to one side or the other, the ear that
• is further from the longtudinal axis still obtains some of the dimensional effect, but' at a reduced level. However, it is believed that the other ear, which is moved across the longitudinal axis has lost a substantially greater amount of the dimensionalized effect. The psychological result of this is that the person will tend to move his head back in the direction of the ear which has lost more of the dimensionalized effect. In other words, the person will tend to move his head back toward the longitudinal axis so that the ear nearest- to the longitudinal axis will move, back across the. longitudinal axis and obtain more of the dimensionalized effect.
With regard to the various frequency equalizers modifying the intensity of the sound as a function of frequency (as shown in Figures 5 and 6) , the values which were finally selected resulted from an empirical analysis of trying various combinations of sound intensities. The substantive effect produced on the listener by the frequency/ intensity pattern disclosed herein is believed by the inventor to be quite satisfactory. However, variations could be made to modify the effect to suit the individual listener.
The approximate range for time delay increments can be varied, and the amount of variation will depend to some extent on the relative. intensity of the main signal component and the compensating signal components . In general , the ranges are believed to be approximately as follows: • ■ time delay time ' distance delay range """ .. increment (inches) tl 1-3 t2 • 2-4. t3 3-7 t4 6-12
(f) Reflected Sound
It was indicated earlier herein that one of the problems of the prior art systems known to the applicant was that reflected sound caused substantial deterioration of the dimensional effect. In the present invention it is noted
-BUREΛ Γ
_ 01PI that each combined signal emitted from the summing junctions C(L) and C(R) is directed back through a time delay device D(L) or D(R) back to the input source L(IN) or R(IN). The amount of time delay is 800 microseconds , which • is moderately longer than the longest time delay increment of the time delay frequency equalizers b4(RL) and b4(LR). The effect of this is to direct the ., . total signal (the main signal plus the compensating signal), back through the system. In addition, the total signal is not only directed back through the same summing junction, but is also directed through the crossover circuit to the opposite summing junction. One of the primary reasons for this is that the reflected sounds should also be compensated for to some extent. In many circumstances, the stereo speakers are placed on the floor, close to the floor, or possibly in a corner. Accordingly, it is expected that sound will be reflected off the floor and/or walls and be directed to the hearer at a time delay in the order of possibly one millisecond, or so. It is believed that this feedback mechanism D(L) and D(R), being fed back through the system and delayed, at least partially compensate for this reflected sound.
It is to be understood, of course, that the above analysis is not intended to be thoroughly exhaustive of the matter. As indicated previously, regardless of the validity or accuracy of this analysis , it has been found that the apparatus does produce this dimensionalized effect and shows a reasonable tolerance to angular and positional deviations of the person's head location.
' (g) Apparatus of the Second Embodiment The recording apparatus of the present invention is illustrated in Figure 10. There are left and right input terminals L(IN) and R(IN). the signal inputs to these terminals L(IN)- and R(i;N) should be stereo signals, such as those produced at the microphones"Ml and M2 of Figure 1. There' are at least two ways to accomplish this, one of which is indicated in full lines of Figure ιo, and the other in broken lines in Figure 10. One method is to use the recording set-up as indicated in Figure 1, 'and attach the two spaced microphones Ml and M2 to respective input terminals L(IN) and R(IN). Thus, the two terminals L(IN) and R(IN) receive stereo signals, where there are corresponding sound components in each signal, with time delays and intensity changes between the corresponding components of the signal. An alternate method of providing the inputs to the terminals L(IN) and R(IN) is simply to take a stereo recording which is made according to the system of Figure 1, and play this recording on a stereo player. Then, instead"of directing, the signals produced by the player to speakers , these signals are directed to the input terminals L(IN) and R(IN). This method is indicated in broken lines in Figure 4-.
The left and right signals are in turn trans¬ mitted directly from terminals L(IN) and R(IN) to left and right frequency equalizers, designated
A(L) and A(R) , respectively. Each of these frequency equalizers A(L) or A(R) is- or may be any one of those- well known in the prior ar , and each functions to control the power of the output as a function of frequency. The output from the frequency equalizer A(L) is directed to a summing junction C(L) and thence to a stereo recorder. In like manner, the output from the right frequency equalizer A(R) is directed through a right summing junction. C(R) to the _ stereo recorder. Additionally, the left stereo input from L(IN) is directed to an inverting device B(LR) which inverts the phase of the signal at L(IN) by 180 . The output from the inverting device B(LR) is in turn transmitted through four channels to four time delay frequency equalizers, designated bl(LR), b2(LR), b3(LR) and b4-(LR), respectively. Each time delay frequency equalizer, bl (LR)-b4-(LR) has two functions, first, to change magnitude of the inverted signal as a function of frequency, and secondly to delay the signal by a predetermined amount of .time.
The collective output of the four time delay frequency equalizers bl(LR) through b4-(LR) provides a compensating signal which is -transmitted to the right summing junction C(R). This left-to-right stereo signal is superimposed over the main right stereo signal output from the right frequency equalizer A(R) , and this combined signal in turn is transmitted to the stereo recorder. In like manner, the right -stereo input signal at R(IN) is transmitted through an inverting device B(RL) which inverts the signal by 180 . The output from the inverting device B(RL) is transmitted along four channels to a second set of four time delay equalizers, designated bl(RL), b2(RL), b3(RL), and b4(RL). As with the other time delay frequency equalizers bl(RL) through b4(LR), the function of the second set of time delay frequency equalizers bl(RL) through b4-(RL) is to provide a right to left compensating signal that is transmitted to the left summing junction C(L) . The compensating signal transmitted to the left summing junction C(L) is superimposed over the main left stereo output from the frequency equalizer A(L) to provide a combined signal which also is transmitted to the stereo recorder. In other respects the apparatus of Figure 10 is substantially similar to the apparatus of Figure 3, so the description of the apparatus of Figure 10 will not be carried further."
To describe the operation of the present invention, reference is made to Figure 2. Let it be assumed that the sound recording made in the stereo recorder by the apparatus of Figure 10 is now placed upon a stereo player which in turn is connected to two speakers LS and RS . The stereo player and the two speakers LS and RS can be a conventional player and speakers such as those well known in the prior art. The player has the capability of taking one of the signals on the sound recording and transmitting this to one speaker LS to reproduce a sound relating to that first signal,, and to take the second signal and direct it to the other speaker RS to produce a second sound corresponding to that second signal. It can readily be appreciated that the sounds produced by the speakers of Figure 2 are in this instance substantially the same as the sounds produced by the speakers of Figure 3, so no further explanation of these will be added.

Claims

Claims
1. A dimensionalized audio signal producing apparatus adapted to be used in conjunction with a pair of speakers, where the following conditions exist: (a) there is a playing area,
5 (b) in said playing area there is a forward transmitting area where there are right and left speakers positioned at right and left speaker locations on a base axis* and spaced from one another on said base axis by a speaker spacing
10 distance,
(c) there is a longitudinal axis positioned equally distant from said speaker locations and perpendicular to said base axis,
(d) there is a listening area at the center •15 of which is a listening location positioned on said longitudinal axis rearwardly of said base axis ,
(e) there is a right listening axis extending from said listening location to said right speaker
20 location at a right listening angle to said longi¬ tudinal axis ,
(f) there is a left listening axis extending from said speaker location to said left speaker location at a left listening angle to said longi-
25 tudinal axis ,
(g) there are right and left ear locations corresponding to right and left ear positions of a person's head which could be located at said listening location and facing forwardly
30 along said longitudinal axis to said base axis, said right and left ear locations being spaced from one another by an ear spacing distance, said apparatus comprising:
(a) left input means to receive a left stereo signal,
(b) right input means to receive a right stereo signal,
(c) left signal output means to produce an audio signal for a left speaker, (d) right signal output means to produce an audio signal for a right speaker,
(e)- left main transmitting means to transmit a left main signal component, corresponding and similar to the left stereo signal, to the left signal output means,
(f) right main transmitting means to transmit a right main signal component , corresponding to and similar to the right stereo signal, to the right signal output means, (g) left to right compensating means adapted to receive said left stereo signal to produce an inverted and delayed left to right -compensating signal , corresponding to said left stereo signal and to transmit said left to right compensating signal to said right signal 'output means,
(h) right to left compensating means adapted to receive said right stereo signal to produce an inverted and delayed right to left compensating signal corresponding to said right stereo signal, and to transmit said right to left compensating signal to said right signal output means,
(i) said two compensating' signals each being delayed relative to corresponding main signal components by a time delay period within a predeter- mined time delay range, the means of said apparatus being constructed, arranged and related to one another in a manner that said left output means produces a left audio signal comprising said left main signal component and said right to left compensating signal, and said right signal output means produces a right audio signal comprising said right main signal component and said left to right compensating signal, so that when said left audio signal drives the left speaker and said right audio signal drives the right speaker, the following occurs
(a) there is a left audio output having a main left sound component and a right to left compensating sound component, said left audio output having a primary path component from said left speaker to said left ear location, and a secondary path component from said left speaker to said right ear location,
(b) there is a right audio output having a main right sound component and a left to right' compensating sound component, said right audio output having a primary path component from said right speaker to said right ear location, and a secondary path component from said right speaker location to said left ear location,
(c) the main left sound component reaches the left ear location without being cancelled to a substantial amount,
(d) the right main sound component reaches the right ear location without being cancelled to a substantial amount, (e) the main left sound component travelling its secondary path to said' right ear location is cancelled to a substantial amount by the left 100 to right compensating sound component travelling on the primary path from said right speaker to said right ear location,
(f) the main right sound component travelling on the secondary path from said right speaker
105 to said left, ear location is cancelled to a sub-" stantial- amount by the right to left compensating sound component travelling from said left speaker along the left primary path to the left ear location, whereby a person positioned so that the person's - 110 head is at the listening location facing along the longitudinal axis toward the transmitting area hears a dimensionalized sound with apparent sound sources being outside of the transmitting area of the two speakers .
2. The apparatus as recited in claim 1, wherein there is for each time delay period a time delay distance, which is that distance that sound travels during the corresponding time delay period, said
5 apparatus being further characterized in that the time delay range for the compensating signals has a smaller time delay limit with a corresponding smaller time delay distance limit, and a larger time delay limit having a corresponding larger
10 time delay distance limit, the smaller and larger time delay distances encompassing a range which includes an optimum time delay distance equal to a value obtained by multiplying the sine of either listening angle times the ear spacing distance.
3. The apparatus as recited in claim 2, wherein each of said compensating signals has a plurality of compensating signal components , each having a different corresponding time delay distance component, at least one of' said time delay distance components being smaller than said optimum time delay distance.
4. The apparatus as recited in claim 2, wherein each of said compensating signals has a plurality of compensating signal components , each having a different corresponding time delay distance component, at least one of said time delay distance components being greater than said optimum time delay distance .
5. The apparatus as recited in claim 2, wherein each of said compensating signals has a plurality of compensating signal components , each haying a different corresponding time delay distance component, at least one of said time delay distance components being greater than said optimum time delay distance, and at least one other of said time delay distance components being smaller than the optimum time delay distance .
6. The apparatus as recited in claim 5, wherein . at least some of said compensating signal components have decibel values lowers than a decibel value of its corresponding main sound component.
7. The apparatus as recited in claim 6, wherein at least one of said compensating signal components has a decibel value which varies with frequency, with lower frequencies of that compensating signal component having a higher decibel level than at higher frequencies of that compensating signal component..
8. The apparatus as recited in claim 1, wherein said left and right main transmitting means comprises frequency equalizer means , each of said f equency equalizer means producing its main signal component having a higher decibel level for lower frequencies and a lower decibel level for higher frequencies.
9. The apparatus as recited in claim 1, wherein there are left and right feedback means to receive respective left and right feedback signals from the left and right signal output means respectively, and transmit feedback signals to, respectively, the left and right input means, said feedback signals being delayed by a time period at least as great as a time delay period of the compensating signals.
10. The apparatus as recited in claim 9, wherein the time delay period for the feedback signals is greater than the time delay periods of the compensating signals .
'
Figure imgf000048_0001
11. The. apparatus as recited in claim 1, wherein there is for each time delay period a time delay distance, which is that distance that sound travels during the corresponding time delay period, there is further an optimum time delay distance equal to a value obtained by multiplying the sine of either listening angle times the ear spacing distance, each of said compensating signals having a plurality of compensating signal components , each having a different corresponding time delay distance component, at least some of said compen¬ sating signal components having a time delay distance between one and twelve inches .
12. The apparatus as recited in claim 11, wherein at least one.of said compensating signal components has a time delay distance between one to three inches .
13. The apparatus as recited in claim 11, wherein at least one of said compensating signal components has a time delay distance between two to four inches . .
14. The apparatus as recited in claim 11, wherein at least one of said compensating signal components has a time delay distance between three to seven • inches .
15. The apparatus as recited in claim 11, wherein at least one of said compensating signal components has a time delay distance between six to twelve inches .
- E 2219
-48-
15. The- apparatus as recited in claim 11, wherein there is for each compensating signal at least ■ four compensating sound components, namely a first compensating sound component having a time delay distance between one to three inches, a second compensating signal component having a time delay distance between two to four inches, a third compensating signal component having - a time delay distance between three to seven Q inches, and a fourth compensating signal component having a time delay distance range between six to twelve inches.
17. The apparatus as recited in claim 1, wherein said right and left main transmitting means each comprises frequency equalizer means which produces the related main signal component in a manner -that certain frequency portions of the related main signal component are varied as a function of frequency.
18. The appartus as recited in claim 17, wherein the main signal components are modified in a ' ' manner that lower frequency portions are of rela¬ tively .greater intensity than higher frequency portions .
19. The apparatus as recited in claim 1, wherein each of said left to right compensating means comprises inverting means to invert a related stereo signal, and a plurality of frequency equalizer means to delay an inverted signal from the inverter
- RE _ g:
means and produce a plurality of compensating signal components having different time delay periods.'
20. The apparatus as recited in claim 1, wherein
(a) said right and left main transmitting means each comprises frequency equali-zer means which produces the related main signal component in a manner that certain frequency portions of the related main signal component are varied as a function of frequency,
(b) the main signal components are modified in a manner that lower frequency portions are of relatively greater intensity than higher frequency portions,
(c) each of said left to right compensating means comprises inverting means to invert* a related stereo signal, and a plurality of frequency equalizer means to delay an inverted signal from the inverter means and produce a plurality of compensating signal components having different time delay periods,
21. The apparatus as recited in claim 17, wherein there is for each compensating means switch means to control intensity of the stereo signal received, so as to increase or decrease compensating effect of the related compensating means .
22. The apparatus as recited in claim 1, wherein:
(a) said right and left main transmitting means each comprises frequency equalizer means which produces the related main signal component
I U EA in a manner that certain frequency portions of the related main signal component are varied as a function of frequency,
(b) each' of said left to right compensating means comprises inverting means to invert a related stereo signal, and a plurality of frequency equalizer means to delay an inverted signal from4 the inverter means and produce a plurality of compensating .- - signal components having different time delay periods, (c) at least some of said compensating signal components having a time delay distance between one and twelve inches .
23. The apparatus as recited in claim 22, wherein at least one of said compensating signal components has a time delay distance between one to three inches .
24-. The apparatus as recited in claim 22, wherein at least one of said compensating signal components has a time delay distance between two to four inches.
25. The apparatus as recited in claim 22, wherein at least one of said compensating signal components has a time delay distance between three to seven inches .
26. The apparatus as recited in claim 22, wherein at least one of said compensating signal components has a time delay distance between six to twelve inches . 27. The apparatus as recited in claim 22, wherein there is for each compensating signal at least four compensating sound components, namely a first compensating sound components having a time delay distance between one to three inches, a second compensating signal component having a time delay distance between two to four inches , a third compensating signal component haying -.__ _ a time delay distance between three to seven inches, and a fourth compensating signal component having a time delay distance range between six to twelve inches .
28. The apparatus as recited in claim 27, wherein:
(a) the main signal components are modified in a manner that lower frequency portions ■ are of relatively greater intensity than higher frequency portions ,
(b) at least some of said compensating signal components have decibel values lower than a decibel value of its corresponding main sound component ,
(c) at least one of said compensating signal components has a decibel value which varies with frequency, with lower frequencies of -that compen¬ sating signal component having a higher decibel level than at higher frequencies of that compensating signal component.
29. The apparatus as recited in claim 28, wherein there are left and right feedback means to receive respective left and right feedback signals from the left and right -signal output means, respectively, and transmit feedback signals to, respectively, the left and right input means , said feedback signals being delayed by a time period at least as great as a time delay period of the compensating signals .
30. A method of producing a dimensionalized audio signal adapted to be used in conjunction with a pair of speakers , where the following conditions exist: - -(a) there is a playing area,
(b) in said playing area there is a forward transmitting area where there are right and left speakers positioned at right and left speaker locations on a base axis and spaced from one another on said base axis by a speaker spacing distance,
(c) there is a longitudinal axis positioned equally distant from said speaker locations and perpendicular to said base axis , (d) there is a listening area at the center of which is a listening location positioned on said longitudinal axis rearwardly of said base axis ,
(e) there is a right listening axis extending ' from said listening location to said right speaker location at a right listening angle to said longi¬ tudinal axis,
(f) there is a left listening axis extending from said speaker location to said left speaker location at a left listening angle to said longi¬ tudinal axis ,
-BU TT (g) "there are right and left ear locations corresponding to right and left ear positions of a person's head which could be located at said listening location and facing forwardly along said longitudinal axis to said base axis , said right and left ear locations being spaced from one another by an ear spacing distance, said method comprising: (a) directing a left stereo signal to left input means ,
(b) directing a right stereo signal to right input means ,
(c) transmitting a left main signal component, corresponding and similar to the left stereo signal, to a left signal output means,
(d) transmitting a right main signal component, corresponding to and similar to the right stereo signal , to a right signal output means , (e) producing from said left stereo signal an inverted and delayed left to right compensating signal, corresponding to said left stereo signal, and transmitting said left to right compensating signal to said right signal output means, (f) producing from said right stereo signal an inverted and delayed right to left compensating signal , corresponding to said right stereo signal , and transmitting said right to left compensating signal to said left signal output means, (g) said two compensating signals each being delayed relative to corresponding main signal - components by a time delay period within a predeter¬ mined time delay range, -54-'
the steps of said method being so arranged and related to one another in a manner that said left signal output means produces a left audio signal comprising said left main signal component and said right to left compensating signal , and said right signal output means produces a right audio signal comprising said right mai"- signal component and said left to right compensating . . signal, so that when said left audio signal drives the left speaker and said right audio signal drives the right speaker, the following o.ccμrs * (a) there is a left audio output having a main left sound component and a right to left compensating sound component, said left audio' output having a primary path component from said left speaker to said left ear location, and a ' secondary path component from said left speaker to said right ear location-,.. - - -
(b) there is a right audio output having a main right sound component and a left to right • compensating .component, said right audio output having a primary path component from said right
■ speaker .to said right ear location, and a secondary path component from said right speaker location • to said left ear location,
(c) the main left sound component reaches the left ear without being cancelled to a substantial amount,
(d) the right main sound component reaches the right _ ear location without being cancelled to a substantial amoun , ' (e) the main left sound component travelling its secondary path to said right ear location is cancel-led to a substantial amount by the left to right compensating sound component travelling on the primary path from said right speaker to
95 said right ear location,
(f) the main right sound component travelling on the secondary path from said right speaker to said left ear location is cancelled to a sub¬ stantial amount by the right to left compensating
100 sound component travelling from' said left speaker * along the left primary path to' the left ear location, whereby a person positioned so that the person's head is at the listening location facing along the longitudinal axis toward the transmitting
1.05 area hears a dimensionalized sound with apparent sound sources being outside of the transmitting area of the two ΞDeakers .
31. The method as recited in claim_30, wherein there is for each time delay period a time delay distance , which is "that distance that sound travels during the corresponding time delay period, said .method being further characterized in. that the time delay range for the compensating signals has a smaller time delay limit with a. corresponding smaller time delay distance limit, and a larger time delay limit having a corresponding larger
10 time delay distance limit, the smaller. and larger time delay distances encompassing a range which includes an optimum time delay distance equal to a value obtained by multiplying the sine of either listening angle times the ear spacing
15 distance. 32. The method as recited. in claim 31, wherein each of said compensating signals has a plurality of compensating signal components, each having a different corresponding time delay distance component, at least one of said time delay distance components being smaller than said- optimum time delay distance .
33. The method as recited in claim 31, wherein each of said compensating signals has a plurality of compensating time delay distance components, at least one of said time delay distance components being greater than said optimum time delay distance .
34. The method as recited in claim 31, wherein each of said compensating signals has a plurality of compensating signal component, each having a different corresponding time delay distance component , at least one of said time delay distance components being greater than said optimum time delay distance, and at least one other of said time delay distance components being smaller- than the optimum time delay distance.
35. The method as recited in claim 34-, wherein at least some of said compensating signal components have decibel values lower than a decibel 'value of its corresponding main sound component .
36. The method as recited in claim 35, wherein at least one of said compensating signal components has a decibel value which varies with frequency, with lower frequencies of that compensating signal component having a higher decibel level than at higher frequencies of that compensating signal component .
37. The method as recited in claim 30, further comprising producing main signal components having a higher. decibel level, for lower frequencies* _ and a lower decibel level for higher frequencies.
38. The method as recited in claim 30, further comprising producing left and right feedback signals from the left and right signal output means respectively, and transmitting feedback signals to, respectively, the left and right
* input means , said feedback signals being delayed by a time period of least as great as a time delay period of the compensating signals.
39. The method as recited in claim 38, wherein the time delay period for the feedback signals, is greater than the time delay periods, of the compensating signals .
40. The method as recited in.claim 30, wherein there is for each time delay period a time delay distance, which is that distance that sound travels during the corresponding time delay period, there is further an optimum time delay distance equal to a value obtained by multiplying the sine of either listening angle times the ear spacing distance , each of said compensating signals having a plurality of compensating signal components, -58-
each having a different corresponding time delay distance component, at least some of said compen¬ sating signal components having a time delay distance between one and twelve inches.
41. The method as recited in claim 4-0, wherein at least one of said compensating signal components has a time- delay. distance between one to three . inches .
42. The -method as recited in claim 40, wherein at least one of said compensating signal components has a time delay distance between two to four inches .
43. The method as recited in claim 40,. wherein at least one of said compensating signal components has a time delay distance between three to seven inches .
44.. The method as recited in claim 40,- wherein at least one of said' compensating signal components has a time delay distance, between six to twelve"' inches ,
45. The method as recited in claim 40, wherein there is for each compensating signal at least four compensating sound components , namely a first compensating sound component having a time delay distance between one to three inches , a second compensating signal component having a time delay distance between two to four inches , a third .compensating signal component having a time delay distance between three to seven . inches , and a fourth compensating signal component having a time' delay distance range between six to twelve inches.
46. The method as recited in claim 30, wherein the signal •components are modified in a manner that certain frequency portions of the related main signal component are varied as a function of frequency. '
47. The method as recited in claim 46, wherein the main signal components are modified in a manner that lower frequency portions are of rela¬ tively greater intensity than, higher frequency portions .
48 ». The method as recited in claim 30 , - comprising:
(a) producing" main signal component in a manner that certain frequency portions of the related main signal component are varied as a * - function of frequency.
(b) modifying the main signal components in a manner that lower frequency portions are a relatively greater intensity than higher frequency portions .
49. A dimensionalized audio signal producing apparatus adapted to be used to produce dimension¬ alized sound from right and left stereophonic signals having corresponding signal components , at least some of which have substantial phase shift therebetween, where the following conditions exist:
( a) there is a forward playing area where there are right and left speaker locations , 0 (b) there is a listening area with a listening location positioned rearwardly of said playing area ,
(c) there are .right and left ear locations corresponding to right. and left ear positions 5 of a person's head which could be located at said listening location and facing forwardly toward said playing area, said apparatus comprising:
(a) left input means to receive a left stereo 0 signal,
(b) right input means to receive a right stereo signal ,
(c) left signal output means to produce an audio signal, for left speaker means at said 5 left speaker Iσcation,
(d) right signal output means to produce
* - an audio signal for right speaker means* at said right speaker location, .-* . . -
(e) left main transmitting- means to transmit 0 a left main signal * component, -corresponding and similar to the left stereo signal, to the left signal output means to produce a left main audio component,
(f) right main transmitting means to transmit 5 a right main signal component, corresponding to and similar to .the right stereo signal, to the right signal output means to produce a right main audio component , (g) -left to right compensating means adapted
40 to receive said left stereo signal to produce an inverted left to right compensating signal corresponding' to said left stereo signal, and to transmit said left to right compensating signal to said right signal output means to produce
45 a left to right compensating audio component,
.(h) right to -left compensating means adapted to receive said right stereo signal to produce an inverted right to left compensating signal corresponding to said right stereo signal, and
50 to transmit said right to left compensating signal to said right signal output means to produce ~" a right to left compensating audio component,
(i) said two compensating audio components each having a time delay distance relative to
55 corresponding main audio components within a* 'predetermined time delay range, the means of said apparatus being constructed, arranged and related to one another in a manner that: • %
60 (a)' said left .main audio component has a primary path component from* said left speaker means to said left ear location, and a secondary path component from said left speaker means to said right ear location,
65 (b) said right main audio component has a primary path component from said right speaker means to said right ear location, and a secondary path component from said right speaker means to said left ear location,
70 (c) the main left audio component reaches the left ear location without being cancelled a substantial amount, (d) the right main audio component reaches 75 the right ear location without being cancelled a substantial amount,
(e) the main left audio component travelling its secondary path to said right ear location is cancelled to a substantial amount by the left 80 to right-, compensating audio -component travelling from said right speaker means to said right ear * location,
(f) the main right audio component travelling on its secondary path to said -left ear location
85 is cancelled to a substantial amount by the right to left compensating audio component travelling from said left speaker means to the left ear location, whereby a person positioned so that the person's
90 head is at the listening location facing toward the transmitting area hears a dimensionalized sound with apparent sound sources being outside the playing area of the two speaker means .
50. The apparatus as recited in claim 49 , wherein -- each of said compensating signals has a plurality of compensating signal components, each having a different corresponding time delay distance 5 ' component , at least one of said time delay distance components being smaller than a time delay distance which provided optimum cancellation at said ear locations . ' '
51. The apparatus- as recited in claim 49, wherein each of said compensating signals has a plurality of compensating signal components , each having a different corresponding time delay distance component , at least one of said time delay distance components being greater than a time delay distance which provides optimum cancellation at said ear location.
52. The apparatus .as recited in claim 49, wherein each of said compensating signals has a plurality of compensating signal components , each having a different corresponding time delay distance component, at least one of said time delay distance components being greater than an optimum time delay distance, and at- least one other of said time delay distance components being smaller than the optimum time delay distance, said optimum time delay distance providing optimum cancellation at said ear locations .
53. The apparatus as recited in claim 52, wherein at .least some of said compensating signal components have decibel values lower than a decibel value of its corresponding main signal .component.
54. The apparatus as recited in claim 53, wherein at least one of said compensating signal components has a decibel value which varies with frequency, with lower frequencies of that compensating signal component having a higher decibel level than at higher ' frequencies of that compensasting signal component . 55. The appartus as recited in claim 49, further comprising frequency equalizer means, said frequency equalizer means producing main signal components having a higher decibel level for lower frequencies and a lower decibel level for higher frequencies.
56. The apparatus as recited in claim 49 , wherein each of said compensating means comprises inverting' means to invert a related stereo signal, and a plurality of frequency equalizer means to delay an inverted signal from the inverting means and produce a plurality of compensating signal components -having different time delay periods.
57. An audio system adapted to produce dimension¬ alized sound from right and left stereo signals which are characterized in that there are corres¬ ponding signal -components , at least some of which have substantial phase shift therebetween, where the following conditions exist:
(a) there .is a foward transmitting area "where 'there are right and left speaker locations ,
(b) there is a listening 'area with a listening location positioned rearwardly of said playing area,
(c) there are" right and left ear locations corres¬ ponding to right and left ear positions of a person's head which could be located at said listening location and facing forwardly toward said playing area said system comprising:
(a) left main transmitting means to receive said left stereo signal and provide a left main stereo output signal,
(b) a right main transmitting means to receive said right stereo signal and provide a right main stereo output signal,.
(c) a left to right compensating means to receive said left stereo signal to produce an inverted left to right compensating signal corres-- ponding to said .lef stereo signal, . ... -• ■__' - - ' "> . . (d) a right to left compensating means to receive said right stereo signal to produce an inverted right to left compensating signal corres¬ ponding to said right stereo signal,
(e) left audio output means to receive said left main stereo output signal and said right to left compensating signal to produce: 1. a left main audio component corresponding to said left main stereo output signal,
2. a right to left compensating audio component corresponding to said left to right compensating signal", - (f) right audio output means to receive said right main stereo output signal., and said left to right compensating signal to produce:
1. a right main audio component corresponding to said right main stereo output signal, 2. a left to right compensating audio component corresponding to said left to right compensating signal,
(g) said compensating means and said audio output means being arranged such that, each of said two compensating audio components has a predetermined time delay distance relative to its corresponding main audio component within a predetermined time delay range, the means of said system being constructed, arranged and related to one another., in a manner that:
(a) said left main audio component has a . primary path component from said left speaker location to said left ear location,
-(b) said right main audio component has a primary path component from said right speaker location to said right ear location, and a secondary path component from said right speaker location' " to said left ear location,
(c) the main left audio component reaches the left ear location without being cancelled' a substantial amoun ,
(d) the right main audio component reaches the right ear location without being cancelled a substantial amount , ■ (e) the main left audio component travelling its secondary path to said right ear location is cancelled to a substantial amount by the left to right compensating sound component travelling from said right audio output means to said right " ear location,
(f) -the main right sound component travelling on the secondary path to said left ear location is cancelled to a substantial amount-by the right to left compensating sound component travelling from said left audio output means to the left ear location, whereby a person positioned so that the person ' s head is at the listening location facing toward the transmitting area hears a dimensionalized sound with apparent sound sources being outisde of the transmitting area of the two speaker locations. 58. The apparatus as recited in claim 57, wherein said compensating signals are so arranged that each compensating audio component has a plurality of compensating audio component portions , each having a different corresponding time delay distance component, at least one of* said time delay distance components being smaller than a time delay distance which provides optimum cancellation at .said ear locations . *
59. The apparatus as recited in claim 57 wherein said compensating signals are so arranged that each compensating audio component has a plurality of compensating audio component portions, each having a different corresponding time delay distance component, at least one of said time delay distance compnents being greater than a time delay distance ' which provides optimum cancellation at said ear location.
60. The appartus as recited in claim 57, wherein said compensating signals are so arranged that each compensating audio component has a plurality of compensating corresponding time delay distance components, at least one of said time delay distance components being greater than an optimum time delay distance, and at least one other of said time delay distance components being smaller than the optimum time delay distance, said optimum time delay distance providing optimum cancellation at said ear locations . 61. The apparatus as recited in claim 60, wherein at least some of said compensating audio component portions have. decibel values lower than a decibel value of its corresponding main audio component.
62. The apparatus as recited in claim 61, wherein at least one of said compensating audio component portions has a decibel value which varies' with
"frequency, with lower frequencies of that compen¬ sating audio component portion having a higher decibel level than at higher frequencies of that compensating signal component.
63. The apparatus as recited in claim 57, further comprising frequency equalizer means, said frequency equalizer means producing main audio components having a higher decibel level for lower frequencies and a lower decibel level for higher frequencies .
64. The apparatus as recited in claim 57, wherein each of said• compensating means comprises inverting means to invert a related stereo signal , and a plurality of frequency equalizer means to delay an inverted signal from the inverter means and produce a plurality of compensating signal components having different time delay periods.
65. An audio system adapted to produce dimension¬ alized sound from right and left stereo signals which are characterized in that there are corres¬ ponding signal components , at least some of which have substantial phase shift therebetween, said system comprising: -69-
(a) left and right speaker means at right and left speaker locations, respectively, said •
5 speaker means arranged to transmit sounds to a listening location where there are right and left ear locations corresponding to right and left ear positions of a person's head which could be located at said listening location,"
10- (b) left main transmitting means to receive said left stereo signal and provide a left main stereo output signal for- said left speaker means,
(c) a right main transmitting means to receive said right stereo signal and provide a right .5 main stereo output signal for said right speaker means ,
(d) a left to right compensating means to receive said left stereo signal to produce an inverted left to right compensating signal corres-
20 ponding to said lef stereo signal for said right speaker means ,
(e) a right to left compensating means to receive said right stereo signal to produce*"an inverted right to left compensating signal corres-
25 ponding to said right stereo signal for said lef speaker means,
(f) said left speaker means adapted. o receive said left main stereo output signal and said right to left compensating signal to produce:
30 1. a left main audio -component corresponding to said left main stere* output signal,
2. a right to left compensating audio component corresponding to said right to left compensating signal,
BU EAU
S* (g) said right speaker means adapted to receive said right main stereo output signal and said left.to right compensating signal to produce :
1. a right main audio component corresponding to said right main stereo output signal ,
2. a left to right compensating audio component corresponding to said left to right compensating signal,
(h) said system being arranged such that each 'of said two compensating audio components has a predetermined time delay distance relative to its corresponding main audio component within a predetermined time delay range , the' means of said system being constructed, arranged and related to one another in a manner tha : ( a) said lef main audio component has a primary path component rom said left speaker means to said left ear location, and a secondary path component from said left speaker means to said right ear location,
(b) -said right main audio component has a primary path component from ,said right speaker means to said right ear location, and a secondary path component from said right speaker means to said left ear location,
(c) the main left audio component reaches the' left ear .location without being cancelled a substantial amount ,
(d) the right main audio component reaches the right ear location without being cancelled a substantial amount, (e) the main left audio component travelling its secondary path to said right ear location is cancelled to a substantial amount by the left to right compensating audio component travelling from said right speaker means to said right ear location,
(f) the main right sound component travelling on the secondary path to said left ear location is .cancelled to a substantial amount by the right to left compensating audio component travelling from said left speaker means to the left location , whereby a person positioned so that the person's head is at the listening location hears a dimension- alized sound with apparent sound sources being outside of the two speaker locations .
'66. The system as recited in claim 65, wherein said compensating signals are so arranged that each compensating "audio component has a plurality of compensating audio component portions , each having a different corresponding time delay distance component, at least one of said time delay distance components being smaller than a time delay distance which provides optimum cancellation at said ear locations .
67. The system, as recited in claim 65, wherein said compensating signals are so arranged that each compensating audio component has a plurality of compensating audio component" portions , each having a different corresponding time delay distance component, at least one of said time delay distance components being greater ihan a time delay distance which provides optimum cancellation at ear location.
68. The apparatus as recited in claim 65, wherein said compensating signals are so arranged that each compensating signals are so arranged that each compensating- audio component has *a plurality of compensating audio component portions , ' each having a different corresponding time delay distance component, at least one of said time delay distance components being greater than an optimum time delay distance, and at least one other of said time delay distance components being smaller than the optimum time delay distance, said optimum time deiay distance providing optimum cancellation at said ear locations .
69. The apparatus as recited in- claim 68, wherein at least some of said compensating audio component portions have decibel values lower than a decibel value of its corresponding main audio component .
70. The apparatus as recited in.claim 69, wherein at least one of said compensating audio component portions has a decibel value which varies with frequency, with lower frequencies of that compen- sating audio component portion having a higher decibel level than at higher frequencies of that compensating signal component.
71. The apparatus as recited in claim 65, further comprising frequency equalizer means, said frequency equalizer means producing main audio components having a higher decibel level for lower frequencies and a lower decibel level for higher frequencies .
72. The apparatus as recited in claim 65, wherein each of said compensating means comprises inverting means to invert a related stereo signal, and a plurality of frequency equalizer means to delay an inverted signal from the inverter means and produce a plurality of compensating signal components having different time delay periods.
73. A method to produce dimensionalized sound from right and 'left stereo signals which are charac¬ terized in that there are corresponding signal components , at least some of which have substantial phase shift therebetween, where the following conditions exist : "
(a) there is a forward playing area hwere there are right and left speaker locations,
(b) there is a listening area with a listening location positioned rearwardly of said playing area,
(c) there are right and left ear locations corresponding to right and left ear positions of a person ' s head which could be located at said listening location and facing forwardly toward said playing area said method comprising:
(a) receiving said left stereo signal and providing a left main stereo output signal, __— (b) receiving said right stereo signal and providing a right main stereo output signal, (c) providing an inverted left to right compensating signal corresponding to said left stereo signal , (d) providing an inverted right to left compensating signal corresponding to said right stereo signal,
(e) transmitting said left main stereo output signal and said right to left compensating signal _ to left audio output means to produce:
1. a left main audio component corresponding to said left main stereo output signal,
2. a right to left compensating audio component corresponding to said right to left compensating signal ,
(f) transmitting said right main stereo output signal and said left to right compensating signal to right .audio output means to produce:
1. a right main audio component corresponding . to said right main stereo output signal,
2. a left to right compensating audio- component corresponding to said, left to right compensating signal , - '
(g) each of said two compensating audio. compoents having a predetermined time delay distance relative to' its corresponding main audio component . within a predetermined time delay range, with steps of said method being arranged and related to one another in a manner that: (a) said left main audio component has a primary path component from said left speaker location to said left ear location, and a secondary path component from said left speaker location to said right ear location,
* (b) said right main audio component has a primary path component from said right speaker, location to said right ear location, and a secondary path component from .said right speaker" location to said left ear location,
(c) the main left audio component reaches the left ear location without being cancelled a substantial amount ,
(d) the right main audio component reaches the right ear location without being cancelled a substantial amount ,
(e) the main left audio component travelling its secondary path to said right ear location is cancelled to a substantial amount by the left to right compensating audio component travelling from said right audio output means to said right ear location,
(f) the main right 'audio- component travelling' on the secondary path to said left ear location is cancelled to a substantial' amount by the right to left conpensating audio component travelling from said left audio output means to the left ear location, whereby a person positioned so that the person's head is at the listening location facing toward the transmitting area hears a dimensionaliized sound with apparent sound sources being outside of the playing area of the two speaker locations. 74. The method as recited in claim 73, wherein said compensating signals are so arranged that each compensating audio component has a plurality of compensating audio component portions , each having a different corresponding time delay distance component, at least one of said time delay distance components being smaller than a time delay distance which provides optimum cancellation at said -ear '- --- -'■ locations.
75. The method as recited in claim 73, wherein said compensating signals are so arranged that each compensating audio component has a plurality of compensating audio component portions, each having a different corresponding time delay distance component, at least one of said time delay distance components being greater than a time delay distance which provides optimum cancellation at said ear locations .
76. The method as recited in claim' 73, wherein said compensating, signals are so arranged that, each compensating audio component has a plurality of compensating audio component"portions , each having a different corresponding time delay distance component, at least one of said time delay distance components being greater than an optimum time delay distance, and at least one other of said time delay distance components being smaller than the optimum time delay distance, said optimum time delay distance providing optimum cancellation at said ear locations . -77-
77. The method as recited in claim 76, wherein at least some of said compensating audio component portions haye decibel values lower than a decibel value of its corresponding main audio component.
78. The apparatus as recited in claim 77, wherein at least one of the said compensating audio component portions has a decibel value which varies with ... frequency, with lower frequencies of that compen¬ sating audio component portion having a higher decibel level than at higher frequencies of that compensating signal component.
79. The method as recited in claim 73, further comprising frequency equalizing said main audio components so that there is a higher decibel level for lower frequencies and a lower decibel level for.hiσher frec encies .
80. A method to produce dimensionalized sound from right and left stereo signals which are characterized in that there are corresponding signal components , at least some of which have substantial phase shift therebetween, .said method comprising:
(a) providing left and right speaker means at right and left speaker locations, respectively, said speaker means arranged -to transmit sounds
10 to a listening location where there are right and left ear locations corresponding to right_ and eft ear positions of a person's head which could be located at-said listening location, (b) receiving said left stereo signal and providing a left main output signal for said left speaker means ,
(c) receiving said right stereo signal and providing a right main stereo output signal for said right speaker means, (d) receiving said left stereo signal to produce an inverted left to right compensating signal corresponding to said left stereo signal for said right speaker means ,
(e) receiving said right stereo signal to produce an inverted right to left compensating signal corresponding to said right stereo signal for said left speaker means ,
(f) producing at said left speaker means:
1. a left main audio component corresponding to said left main stereo output signal,
2. a right to left compensating audio component corresponding to s-aid right to left compensating signal, (g) producing at said right speaker means:
1. a right main audio .component corresponding to said right main stereo output signal,
2. a left to right compensating audio component corresponding to said left to right compensating signal,
(h) each of said two compensating audio components having a predetermined time 'delay distance relative to its corresponding main audio component .within a predetermined time delay range, with the steps of said method being arranged and related to one another in a manner that : -79-
(a) "said left main audio component has a primary path component from said left speaker means to said left ear location, and a secondary 50 path component from said left speaker means to said right ear location,
(b) said right main audio component has a primary path component from said right speaker means to said right ear location, "and a secondary 55 path component from said. right speaker -means - 'to said left ear location,
(c) the main left audio component reaches the left ear location without being cancelled a substantial amount ,
~5Q (d) the right main audio component reaches the right . ear location without being cancelled a substantial amount,
(e) the main left audio component travelling its secondary path to said right ear location
65 ' is cancelled to a substantial amount by the left to right compensating audio component travelling from said right speaker means to said right ear location,*
(f) the main right sound component travelling 70 on the secondary path to said left ear. location is cancelled to a substantial amount by the right to left compensating audio component travelling from said left speaker means to the left ear location, 75 whereby a person positioned so that the person's head is at the listening location hears a dimension¬ alized sound with apparent sound s ources being outisde of the two speaker locations. — 80-
81. The method as recited .in claim 80, wherein said compensating signals are so arranged that each compensating audio component has a plurality of compensating audio component portions , each
5 having a different corresponding time delay distance component, at least one of said time delay distance components being smaller than a time delay distance which provides optimum cancellation at said ear locations .
82. The method as- recitedin claim 80, wherein said compensating signals are so arranged that each compensating audio component has a plurality of compensating audio component portions , each
5 having a different corresponding time delay distance component , 'at least one of said time delay distance components being greater than a time delay distance which provides optimum cancellation .at said ear locations .
83. The method as recited in claim 80,. wherein said compensating signals are so arranged that each compensating audio component has a plurality of compensating audio' component portions , each
5 having a different corresponding time delay distance component, at least one of said time dealy distance components being greater than an optimum time delay distance, and at least one other of said time delay distance components being smaller
10 than the optimum time delay distance, said optimum time delay distance providing optimum cancellation at said ear locations . -81-
84. The method as recited "in claim 83, wherein at least some of said compensating audio component portions have decibel values lower than a decibel value of its corresponding main audio componen .
85. The apparatus as recited in claim 84', wherein at least one of said compensating audio component portions has a .decibel value, which varies with ** frequency, with lower frequencies of that compen¬ sating audio component portion having a higher decibel level than at higher frequencies -of that compensating audio component portion.
86. The method as recited in claim 80, further., comprising frequency equalizing said main audio components so that there is a higher decibel level for lower frequencies and a lower decibel level for higher frequencies .
87. An apparatus for producing a dimensionalized sound recording adapted to be .used in conjunction with, a stereo player and a pair * of speakers', where the following conditions exist:
(a) there is a playing area
(b) in said playing area there is a forward transmitting area where there are right and left speakers connected to a stereo player and positioned at right and left speaker locations on a base
10 axis and spaced from one another on said base axis by a speaker spacing distance,
(c) there is a longitudinal axis positioned equally distant from said speaker locations and ■82-
perpendicular to said base axis , 15 (d) there is a listening area at the center of which is a listening location positioned on said longitudinal axis rearwardly of said base axis ,
(e)- there is a right listening axis extending 20 from said *listening location to said right speaker location, at a right listening angle to said longi- . tudinal axis., .
(f) there is a left listening axis extending from said listening location to said left speaker
25 location at a left listening angle to said longitu¬ dinal axis,
(g) there are right and left ear locations corresponding to right and left ear positions of a person's head which could be located at
30 said listening location, and facing forwardly along said longitudinal axis to said base axis , said right and l-e t ear locations being spaced from one another" by an ear spacing distance, . said apparatus comprising:
35 (a) left input means to receive a left stereo signal,
(b) right input means to receive a right stereo signal,
(c) left signal output means to produce 40 a left audio signal,
(d) right signal output means to produce a right audio signa ,
(e) left main transmitting- means to transmit a left main signal component , corresponding and
45 similar to the left stereo signal, to the left ■83-
signal output means ,
(f) right main transmitting means to transmit a right main signal component, corresponding to and similar to the right stereo signal, to 50 the right signal output means,
(g) left to right compensating means adapted to receive said left stereo signal to produce an inverted and delayed left to right compensating signal, - corresponding to said left stereo signal
55 and to transmit said left to right compensating signal to said right signal output means,
(h) right to left compensating means adapted to receive said right stereo signal to produce
"~ an inverted and delayed right to left compensating
60 signal corresponding to said right stereo signal, and to transmit said right to left compensating signal to said right signal output means ,
(i) said two compensating signals each being delayed relative to corresponding main signal
65 . components by a time delay period within a predeter¬ mined time delay range,
(j) a stereo recording device operatively connected to said left and right signal output means to receive said left and right audio signals
70 and produce a stereo sound recording from said left and right audio signals whereby said left signal output means produces a left audio signal comprising said left main signal component and said right to left compensating
75 signal, and said right signal output means produces a right audio signal comprising said right main signal component and said left to right compensating • 84- -
signal, so that when said stereo recording is played on a stereo player connected to. right 80 and left speakers, said left audio signal drives the left speaker and said right audio signal drives the right speaker so that the following occurs
(a) there is a left audio output having
85 a main left sound component and a right to left compensating sound component, said left audio output having a primary path component from said left speaker to said left ear location, and a secondary path component from said left speaker
90 to said right ear location,
(b) there is a right audio output having a main right sound component and a left to right compensating componen , said right audio output having a primary path component from said right 95 speaker to said right ear location, and a secondary path component .from said right speaker location to said left ear location,
(c) the main left sound component reaches the lef ear without being cancelled to a substantial 100 amount, - ;
(d) the right main sound component reaches* the right ear location without being cancelled to a substantial amount,
(e) the main left sound component travelling 105 its secondary path to said right ear location is cancelled to a substantial amount by the left to right compensating sound component travelling on the primary path from said right speaker to said right ear location, - 85-
110 ' (f) the main right sound component travelling on the secondary path from said right speaker to said left ear location is cancelled to a substan¬ tial amount by the right to left compensating sound component travelling from said left speaker
115 along the left primary path to the left ear location, whereby a person positioned so that the person's head is at the listening location facing along . _ - the longitudinal axis toward the transmitting area hears a dimensionalized sound with apparent
120 sound sources being outside "or~ the transmitting area of the two soeakers .
88. The apparatus as recited in claim 87, wherein there is for each time delay period a time delay distance, which is that distance that sound travels during the corresponding time delay period, said apparatus being further characterized in that . . the time elay range" for the compensating signals has a smaller time delay limit with a corresponding smaller time delay distance limit, and* a larger time delay limit having a corresponding larger
10 time delay distance limit, the smaller and larger time delay distances encompassing a range which includes an optimum time delay distance equal to a value obtained by multiplying the sine of either listening angle times the ear spacing distance .
89. The apparatus as recited in- claim 88, wherein each of said compensating signals has a plurality of compensating signal components, each having a different corresponding' time delay distance -86-
component , at least one of said time delay distance components being smaller than said optimum time delay distance .
90. The apparatus as recited in claim 88, wherein each of said compensating signals has a plurality of compensating signal components , each having a different corresponding time delay distance component, at least one of said time delay distance components being greater than said optimum time delay distance.
91. The apparatus as recited in claim 88, wherein each of said compensating signals has a plurality of compensating signal component , each having a different corresponding time delay distance components , at least one of said time delay distance components being greater than said optimum time delay distance , and at least one other of said time delay distance components being smaller than the optimum time delay distance..
92. The apparatus as recited ,in claim 88, wherein at least some of said compensating signal components have decibel values lower than a decibel value of its corresponding main sound component.
93. The apparatus as recited in claim 92, wherein at least some of said compensating signal components has a decibel value which varies with frequency, with lower frequencies of that compensating signal component having a higher decibel level than at higher frequencies of that compensating signal component .
94. The apparatus as recited in claim 87, wherein said left and right main transmitting means comprises f equency equalizer means , each of said frequency equalizer means producing its main signal compnent having' higher decibel * level for* lower -frequencies * *•* and a lower decibel level for higher frequencies.
95. The apparatus as recited in claim 87, wherein there are left and right feedback means to receive respective left and right feedback signals from the left and right signal output means respectively, and transmit feedback signals to, respectively the left and right input means, said feedback signals being delayed by a time period at least as great as a time delay period of the compensating signals .
96. The apparatus as recited in claim 95., wherein the time delay period for the feedback signals is greater than the time delay periods of the compensating signal's . . '
97. The apparatus as recited in claim 87, wherein there is for each time delay pejriod of time delay distance, which is that distance that sound travels during the corresponding time delay period, there is further an optimum time delay distance equal to a value obtained by multiplying the ' sine of either listening angle times the ear spacing distance, each of said compensating signals having a plurality of compensating signal components , each having a different corresponding time delay distance component, at least some of said compen¬ sating signal components having a time delay distance between one and twelve inches .
98. The apparatus as recited in claim 97, wherein at least one of said compensating signal components . -- has a time delay distance between one to. hree inches.
99. The apparatus as recited in claim 97, wherein at least one of said compensating signal components has a time delay distance between two to four inches .
100. The apparatus as recitedin claim 97, wherein at least one of said compensating signal components has a time delay distance between three to seven inches.
101. The- pparatus as recited in claim 97, wherein at least one of said compensating signal components has a time delay distance between six to twelve inches .
102. The apparatus as recited in claim 97, wherein there 'is for each compensating signal at least four compensating sound components , namely a first compensating sound component having a time delay distance between one to three inches , a -89-
second compensating signal component having a time delay distance between two to four inches , a third compensating signal component having a time delay distance between three to seven 10 inches , and a fourth compensating signal component having a time delay distance range between six to twelve inches .
-103. The- apparatus as recited in claim 87, wherein ■ said right and left main transmitting means each comprises frequency equalizer means which produces the related main signal component in a manner 5 that certain frequency portions of the related main signal component are varied as a function of frequency.
104. The apparatus as recited in claim 103, wherein the main signal components are modified in a manner that lower frequency portions are of rela¬ tively greater intensity than higher frequency
5 portions . '
105. The apparatus as recited in-claim 87, wherein each of said left to right compensating means comprises inverting means to invert a related stereo signal, and a plurality of frequency equalizer
5 means.
106. The apparatus as recited in claim 87, wherein (a) said right and left main transmitting means each comprises frequency equalizer means which produces the related main signal component 5 in a manner that certain frequency portions of _ΛJ EA{/ o.y.pi /?NATlO - . -90-
th e related main signal component are varied as a function of frequency .
( b ) the main signal components are modified in a manner that lower frequency portions are
10 of relatively greater intensity than higher frequency portions .
( c) each of said left to right compensating means comprises inverting means to invert a related stereo signal , and a plurality of frequency equalizer
15 means to delay an inverted signal from the inverter means and produce a plurality of compensating signal components having different time delay periods .
107 . The apparatus as recited in claim 103 , wherein there is for each compensating means switch means to control . intensity of the stereo signal received , so as to increase or decrease compensating effect
5' of the related compensating means .
108 . The apparatus as recited in claim 87 , wherein : ( a)- said right and left main transmitting* means each comprises frequency equalizer means which produces the related main signal component
5 in a manner that certain frequency portions of the related main signal component are varied as a function of frequency ,
(b) each of said left to right compensating means comprises inverting means to invert a related
10 stereo signal , and a plurality .of frequency equalizer means to delay an inverted signal from the inverter means and produce a plurality of compensating signal components having different time delay periods , -91-
c. at least some of said compensating signal components having a time delay distance between
15 one and twelve inches .
109. The apparatus as recited in claim 108, wherein at least one of said compensating signal components, has a time delay distance between one to three inches .
110. The apparatus as recited in. claim 108 ,' wherein at -least one of said compensating signal componets has a time delay distance between two to four inches .
111. The apparatus as recitedin claim 108, wherein at least one of said compensating signal compo¬ nents has a time delay distance between three to seven inches .
112. The apparatus as recited in claim 108, 'wherein at least one of said compensating signal components has a time delay distance between- six to twelve inches . - •
113. The apparatus as recited in claim 108, wherein there is for each compensating signal at least four compensating sound components , namely a first compensating sound components having a time delay distance between one to three inches , a second compensating signal component having a time delay distance between two to four inches , a third compensating signal component having 10 a time delay distance between three to seven inches , and a fourth compensating signal component * having a time delay distance range between six to twelveinches .
114. The apparatus as recited in claim 113, wherein:
(a) the main signal components are modified in a manner that lower frequency portions are of relatively greater intensity than higher frequency 5 portions ,
(b) at least some of said compensating signal components have decibel values lower than a decibel value of its corresponding main sound component ,
(c) at least one of said compensating signal 10 components has a decibel value which varies with frequency, with lower frequencies of that compensating signal component having a higher decibel- level than at higher frequencies of that compensating signal component .
' 5
115. The apparatus as recited in claim 114, wherein there are left and right feedback means to receive respective left and right feedback signals from the left and right signal output means., respectively, 5 and transmit feedback signals to", respectively, the left and right input means , said feedback signals being delayed by a time period at least as great.as a time delay period of the compensating siσnals . 116. A method of producing -a dimensionalized sound recording adapted to be used in conjunction 'with a stereo player and a pair of speakers, where the following conditions exist: (a) there is a playing area
(b) in said playing area there is a forward transmitting area where there are "right and left speakers connected to said stereo player and positioned at right and left speaker 'locations • on a base axis and spaced from one another on said base axis by a speaker spacing distance,
(c) there is a longitudinal axis positioned equally distant from said speaker locations and perpendicular to said base axis, (d) there is a listening area at the center of which is a listening location positioned on said longitudinal axis rearwardly of said base axis , .. - -_. .. - -
(e) there is a" right listening axis extending from said listening location to said right speaker location at a right listening angle to said longitu¬ dinal axis ,
(f) there is a left listening axis extending from said listening location to said left speaker location at a left listening angle to said longitu¬ dinal axis
(g) there are right and left ear locations corresponding to .right and left ear positions of a person's head which could be located at said listening location and facing forwardly along said longitudinal axis to said base axis, said right and left .ear locations being, spaced -94-
from one another by an ear -spacing distance, said method comprising: (a) directing a left stereo signal to left input means
(b) directing a right stereo signal to right input means
(c) transmitting a left main signal component, corresponding and similar to the left stereo signal, to -a left signal output means,
(d) transmitting a right main signal component, corresponding to and similar to the right stereo - signal , to a right signal output means , (e) producing- from said left stereo signal an inverted and delayed left to right compensating signal , corresponding to said left stereo signal , and transmitting said left to right compensating signal to said right signal output means, (f) producing from said right stereo signal an inverted and delayed right to left compensating signal, corresponding to said right stereo signal, and transmitting said right .to left compensating signal to said left signal output means, (g) said two compensating signals each being delayed relative to corresponding main signal components by a time delay period within a predeter¬ mined time delay range,
(h) directing right and left audio signals from said right and left signal output means to a stereo recorder to produce a sound recording having right and, left information channels , said left information channel comprising said left main signal coπponent and said right to left compen—
BUREAU
' sating signal , and said right information channel comprising said right main signal component and said left to right compensating signal, the steps of said method being so arranged and related to one another in a manner that when said sound recording is played on a stereo player connected to right and left speakers, said left information channel produces sound in the left ' speaker and said right information channel' produces sound in the right speaker, so that the following occurs
(a) there is a left audio output having a main left sound component and a right to left compensating sound component, said left audio output having a primary path component from said left speaker to said left ear location, and a secondary path component from said left speaker to said right ear location,
(b) there is a right audio output having
• ' a main right sound component and .a left to right compensating component ,. said right audio output - having a primary path component from* said right speaker to said right ear location, and a secondary path component from said right speaker- location to said left ear location, (c) the main left sound component reaches the left ear without being cancelled to a substantial amount ,
(d) the right main sound component reaches the right ear location without being cancelled to a substantial amount,
(e) the main left -sound component travelling -96-
its secondary path to said right ear location is cancelled to a substantial amount by the left to right compensating sound component travelling 100 on the primary path from said right speaker to said right ear location,
(f) the main right *sound component travelling . on the secondary path from said right speaker to said left ear location is cancelled .to a substan- 105 tial amount by the right to left compensating sound component travelling from said left 'speaker along the left primary path to the left ear location, whereby a person positioned so that the person's head is at the listening location facing along 110 the longitudinal axis toward the transmitting area hears a dimensionalized sound with apparent sound sources being outside of the transmitting area of the two speakers .
117. 'The method as recited in claim 116, wherein there is for each time delay period a time delay distance, which is that distance that sound travels during the corresponding time delay period, said method' being further characterized in that the time delay range for the compensating signals ** has a smaller time delay limit -with a corresponding smaller time delay distance limit, and a larger time delay limit having a corresponding larger
10 time delay distance limit, the smaller and larger time delay distances encompassing a range which includes an optimum time delay distance equal to a value obtained by multiplying the sine of either listening angle times the ear spacing
15 distance. -97-
118. The method as recited--in claim 117, wherein each of said compensating signals has a plurality of compensating signal components , each having a different corresponding time delay distance component, at least one of said time delay distance components being smaller than said optimum time delay distance.
119. The method as recited in. claim 117, wherein each of said' compensating signals has a plurality of compensating signal components, each having a different corresponding time delay distance component, at least one of said time delay distance components being greater than said optimum time delay distance .
120. The method as recited in claim 117, wherein each of said compensating signals has a plurality of compensating signal component, each having a different corresponding time delay distance component, at least one other of said time delay components being greater than said optimum time delay distance, and at least one said time delay distance components being smaller than the optimum time delay distance.
121. The method as recited in claim 120, wherein at least some of said compensating signal components have decibel values lower than a decibel value of its corresponding main sound, component.
122. The method as recited in claim 121, wherein at least one of said compensating signal components has a decibel value which varies with frequency, with lower frequencies of that compensating signal component having a higher decibel level than at higher frequencies of that compensating signal componen .
123.- The method as recited in claim 116-, further comprising producing main signal components having a higher decibel level for lower frequencies and a lower decibel level for higher f equencies .
124. The method as recited in claim 116, further comprising producing left and right feedback signals from the left and right signal output means respectively, and transmitting feedback signals to, respectively, the left and right input means , said feedback signals being delayed by a time period at least as great as a time delay period of the compensating signals .
125.. The method as recited in claim 124, wherein the time delay- period for the feedback signals is greater than the time delay periods of the compensating signals . . .
126. The method as recited in claim 116, wherein there is for each time delay period a time delay distance, which is that distance that sound travels during the corresponding time delay period, there is further ,an optimum time delay distance equal to a value obtained by multiplying the sine of either listening angle times the ear spacing distance, ' each of said compensating signals having a plurality of compensating signal components , each having a different corresponding time delay distance component , at least some of said compen¬ sating signal components having a time delay distance between one and twelve inches .
127. The method as recited in claim 126, wherein at least one of., said, compensating signal components has a time delay distance between one to three inches . '
128. The method as recited in claim 126, wherein at least one of said compensating signal components has a time delay distance between two to four inches .
129. The method as recited in claim 126, wherein at least one of said compensating signal components has a time delay distance between three to seven inches .
130. The method as recited in claim 126, wherein at least one of said compensating signal components has a time delay distance between six to twelve inches .
131. The method as recited in claim 126, wherein there • is for each compensating signal at least four compensating sound components , namely a first compensating sound component having a time delay distance between one to three inches , a -100-
second compensating signal •component having a time delay distance between two to fourinches , a third compensating signal component having a time delay distance between three to seven inches, and a fourth compensating signal component having a time delay distance range bwtween six to twelve inches .
132. The method .as recited in. claim 116, wherein the signal components are modified in a manner that certain, frequency portions of the related main signal component are varied as function of frequency.
133. The method as recited in claim 132, wherein the main signal components are modified in a manner that lower frequency portions are of rela¬ tively greater intensity than higher frequency portions .
134. The method as recited in claim 116, comprising: (a) producing* main signal component in a manner* that certain 'frequency portions of the realted main signal component are varied as a function of frequency.
(b) modifying the main signal components in a manner that lower frequency portions are of relatively greater intensity than higher frequency portions.
135. A sound recording made according to the method recited in claim 116, said sound recording having left and right information channels, to produce sound in right and left speakers , said sound recording being characterized in that:
(a) said left channel having
1. a left main stereo component having a pattern corresponding and similar to a left stereo input signal 2. a right to left compensating component"** having a pattern -which corresponds to an inverted and delayed pattern of a right stereo input signal ,
(b) said right channel having
1. a right main stereo component having a pattern corresponding and similar to the right stereo input signal
2. a left to right compensating component having a pattern which corresponds to an inverted and delayed pattern of the left stereo input signal .
136 . The sound recording as recited in claim
135 , wherein each of said compensating components has a plurality of compensating sub components , each having a different corresponding time delay distance component , at least one of said time delay distance components being greater than said optimum time delay distance .
137 . A dimensionalized sound recording adapted to be played on a stereo player in conjunction with a - pair of speakers , where- the following conditions exist : ( a ) there is a playing area -102-
(b)*in said playing area there is a foward transmitting area where there are right and left speakers positioned at right and left speaker locations on a base axis and spaced from one another on said base axis by a speaker spacing distance,
(c) there is a longitudinal axis positioned equally distance from said-_speaker locations and perpendicular to said base axis , (d) there is a listening area at the center of which is a listening location positioned on said longitudinal axis rearwardly of said base axis ,
(e) there is a right listening axis extending from said listening location to said right speaker location at a right listening angle to said longitu¬ dinal axis ,
(f) there is a left listening axis extending . from said listening location to said left speaker location at a "left listening angle to said longitu¬ dinal axis
(g) there are right and left ear locations
• corresponding to right .and left ear positions of a person's head which is "located at said listening location and facing forwardly along said longitudinal
• axis to said base axis , said right and lef ear locations being spaced from, one another by an ear spacing distance , said sound recording having left and right infor- mation channels , to produce sound in right and left speakers , said sound recording being character¬ ized in that: (a) said left channel -having 1. a left main stereo component having
" a pattern corresponding and similar to a left stereo input signal
2. a right to left compensating component having a pattern which corresp.onc." to an inverted and delayed pattern of a right stereo input signal,
(b) said right channel having
1. a right main stereo component having a pattern corresponding and similar to the right stereo input signal 2. a left to right compensating component having a pattern which corresponds to an inverted and delayed pattern of the left stereo input signal
(c) said two compensating components each being delayed relative to its related main signal • component by a time delay period within a predeter¬ mined time delay range whereby said left channel produces a left audio signal comprising said left main stereo component . and said right to left- compensating component, * - - an said right channel produces" a right audio ' signal comprising said right main stereo component and said left to -right compensating component, so that when said left signal drives the left speaker and said right audio signal drives the right speaker, the following occurs
(a) there is a left audio output having a main left sound component and. a right to left • compensating sound component, said left audio output having a primary path component from said •104-
left speaker to said left ear location, and a secondary path component from said left speaker to said right ear location,
(b) there is a right audio signal having
40 a main right sound component and a left to right compensating component , said right audio output having a primary path component from said right speaker to said right ear location, and a secondary path component from said right speaker location
45 to said left ear location,
(c) the main left sound component reaches the left ear without being cancelled to a substantial .. amoun , " ■
(d) the right main sound component reaches 50 the right ear location without be cancelled to a substantial amount,
(e) the main left sound component travelling its secondary path to said right ear location is cancelled to a substantial amount by the left 55. to right compensating sound component travelling on the primary path from said right speaker to - said right ear location
(f) the main right sound component travelling on the secondary path from said right speaker
60 to said left ear location- is cancelled to a substan¬ tial amount by the right to left compensating sound component travelling from said left speaker along the left primary path to the left ear location, whereby a person positioned so that the person's
65 head is at, the *listening location facing along the longitudinal axis toward the transmitting area hears a dimensionalized sound with apparent sound sources being outside of the transmitting area of the two speakers.
138. The recording as recited in claim 137, wherein there is for each time delay period a time delay distance, which is that distance that sound travels during the corresponding time delay period, said recording being further characterized in that the time delay range for the compensating components has a smaller time delay limit with a corresponding smaller time delay distance limit, and a larger time delay limit having a corresponding larger time delay distance limit, the smaller and larger time delay distance encompassing a range which includes an optimum time delay distance equal to a value obtained by multiplying the sine of either listening" angle times the ear spacing distance.
* • 139. The recording as recited in claim 138 , wherein each of said compensating components has a plurality of compensating' sub components, each having a different corresponding time delay distance com- ponen , at least one of said time delay distance components being smaller than said -optimum time delay distance.
140. The recording as recitedin claim 138, wherein each of said compensating components has a .plurality of compensating sub components," each having a different corresponding time delay distance compo- nent, at least one of said time delay distance components being greater than said optimum time delay distance .
141. The recording as recited in claim 138, wherein each of said compensating components has a plurality of compensating sub components , each having a different corresponding time delay distance compo¬ nent, at least one of said time delay distance components being greater than said optimum time delay distance, and at least one of said"time delay distance components being smaller than the optimum time delay distance.
142. The recording as recited in claim 141, wherein at least some of said compensating" sub components have decibel values lower than a decibel value of its corresponding main sound component.
143. The recording as recited in claim 142, wherein at least one of said compensating sub components has a decibel value which varies with frequency, with lower frequencies of that compensating sub component having a higher decibel level than at. higher frequencies of that compensating sub component.
»
144. The recording as recitedin claim 137, wherein each main stereo component has a higher decibel level for lower frequencies and a lower decibel level for higher frequencies. . 145. The recording as recited in claim 137, wherein each information channel has a feedback component delayed by a time period at least as great as a time delay period of the compensating components .
146. The recording as recited in claim 145, wherein the time delay period for the feedback -components is greater. than the time delay periods of the compensating components .
147. The recording as -recited in claim 137, wherein there is for each time delay period a time delay distance, which is that distance that sound travels during the corresponding time delay period, there
5 is further an optimum time delay distance equal to a value obtained by multiplying the sine of either listening angle times the ear spacing distance , each of said compensating components having a plurality of compensating sub components,
10. each having a different corresponding time delay distance component , at least some of said compen¬ sating, sub components having a time delay distance- between one and twelve inches.
148. The recording as recited in claim 147 , wherein at least one of said compensating sub components has a time delay distance between one to three inches .
149. The recording as recited in claim 147, wherein at least one of said compensating sub components has a time delay distance between two to four inches . 150. The recording as recitedin claim 147, wherei at least one of said compensating sub components has a time delay distance between three to seven inches .
151. The recording as recited in claim 147, where at least one of said compensating sub components has a time delay distance between six to twelve inches . -
152. The recording as recited in claim 147, wher there is for each compensating component at leas four compensating sub components , namely a irsl compensating sub component having a time delay distance between one to three inches , a second compensating sub component having a time delay distance between two to four inches , a third compensating sub component having atime delay distance between three to seven inches , and a fourth compensating sub component having a time delay .distance range between six to twelve inch
153. The recording as recited in claim 137, whe each main stereo -component has amplitude variat from its related stereo input signal.
154. The recording as recited in claim 153, wh« i the main signal components are modified in a manner that lower frequency portions thereof are of relatively greater intensity than highe: <. frequency portions , relative to its related st input signal . -109 -
155 . The recording as recited in claim 137 , wherein ( a) each main stereo component has amplitude variations from its related stereo input signal , as a function of frequency . 5 (b ) the main signal components are modified in a manner that lower frequency portions thereof are of relatively greater intensity than higher frequency portions , relative to its related stereo input signal . _ :- . . .
156 . A dimensionalized sound recording adapted to be played on a stereo player in conjunction with a pair of speakers , where the following conditions exist : 5 ( a ) there is a forward playing area where there are right and left speakers positioned at right and left speaker locations
• (b ) there is a listening location positioned rearwardly of said playing area ^
10 ( c ) there "are right and left ear locations
- corresponding to right and left ear positions of a person ' s head which is located at said listening location .and. facing forwardly , said sound recording having left and right information 15 channels , to produce sound in right and le t speakers , said sound recording being characterized in that : • . *~~~ .
( a) said left channel having
1 . a left main -stereo component having 20 a pattern corresponding and similar to a left stereo input signal
2. a right to left compensating component having a pattern which corresponds to an inverted and delayed pattern of a right stereo input signal , -110-
(b) said right channel having
1. a right main stereo component having a pattern corresponding and similar to the .right stereo input signal
2. a left to right compensating component having a pattern which corresponds to an inverted and delayed pattern of the left stereo -input signal . -
(c) said two compensating components each being delayed relative to its related main signal component by a. time delay period within a predeter¬ mined time delay range , whereby said left channel produces a left audio signal comprising said left main stereo component and said right to left compensating component, and said right channel produces a right audio signal comprising said right main stereo component and said left to right compensating component, so that when said left signal drives the left speaker and said right audio signal drives the right speaker, the following occurs
(a) there is a left audio output having a main left sound 'component and a right to left compensating sound component, said left audio output having a primary path component from said left speaker to said left ear location, and a secondary path component from said left speaker to said right ear location,
(b) there is a right audio output having a main right sound component and a left to right compensating component, said right audio output having a primary path component from said right -Ill-
speaker to said right ear location, and a secondary path component from said right speaker location to said left ear location, 0 (c) the main left sound component reaches the left ear without being cancelled to a substantial amount,
(d) the right main sound component* reaches the right ear location without being cancelled" "* 5 to a substantial amount,
(e) the main left sound component travelling its secondary path to said right ear location is cancelled to a substantial amount by the left to right compensating sound component travelling 0 on the primary path from said right speaker to said right ear location
(f) the main right sound component travelling on the secondary path from said right speaker to said left ear location is cancelled to a sub- stantial amount by the right to left compensating * sound component travelling from said left speaker ■along-the left primary path to the 'left ear location, whereby a person positioned so that the person's head is at the listing location facing along the longitudinal axis toward the transmitting area hears a dimensionalized sound with apparent sound sources being outside of the transmitting area of the two speakers .
157. The recording as recited in claim 156, wherein each of said compensating components has a plurality of compensating sub components , each having a different corresponding time delay distance cpmpo- - nent, at least one of said time delay distance
O.V.Pi
Vv*: 0 ,ώ* component's being smaller than a time delay distance which provides optimum cancellation at said ear locations .
158 . The recording as recited in claim 156 , wherein each of said compensating components has a plurality of compensating time delay distance components , at least one of said time delay distance components being greater than a time delay distance which provides optimum cancellation at said ear locations .
159 . The recording as recited in claim 155 , wherein each of said compensating components has a plurality of compensating sub components , each having a different corresponding time delay distance compo- nsnt , at least one of said time delay distance components being greater than .an optimum time delay distance , and at least one other of said time delay distance components being smaller than the optimum time delay distance , said optimum time delay distance providing optimum cancellation at said ear locations .
160. The recording as recited in claim 159 , wherein • at least some of said compensating sub components have decibel values lower than a decibel value of its corresponding main sound component .
161 . The recording as recited in claim 160 , wherein at least one of said compensating sub components has a decibel value which varies with frequency , with lower frequencies of that compensating sub copponent having a decibel "level higher than at higher frequencies of that compensating sub component.
162. The recording as recited in claim 156, wherein each main stereo component has a higher decibel level for lower frequencies and a lower decibel level for higher frequencies.
PCT/US1980/000354 1979-04-05 1980-04-04 Dimensional sound producing apparatus and method WO1980002219A1 (en)

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US27472 1979-04-05
US06/027,473 US4309570A (en) 1979-04-05 1979-04-05 Dimensional sound recording and apparatus and method for producing the same
US06/027,472 US4218585A (en) 1979-04-05 1979-04-05 Dimensional sound producing apparatus and method

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EP0148568A1 (en) * 1983-11-22 1985-07-17 Sci-Coustics, Inc. Stereo image recovery
EP0282017A2 (en) * 1987-03-13 1988-09-14 Ohno Matsuo Stereo processing system
EP0740487A2 (en) * 1995-04-28 1996-10-30 Yamaha Corporation Stereophonic sound field expansion device
CN113630710A (en) * 2015-09-08 2021-11-09 苹果公司 Stereo and filter control for multi-speaker device

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RU2106073C1 (en) * 1996-02-12 1998-02-27 Владимир Анатольевич Ефремов Spatial sound-reproducing system
JP5206137B2 (en) * 2008-06-10 2013-06-12 ヤマハ株式会社 SOUND PROCESSING DEVICE, SPEAKER DEVICE, AND SOUND PROCESSING METHOD

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EP0036337A2 (en) * 1980-03-19 1981-09-23 Matsushita Electric Industrial Co., Ltd. Sound reproducing system having sonic image localization networks
EP0036337B1 (en) * 1980-03-19 1985-02-20 Matsushita Electric Industrial Co., Ltd. Sound reproducing system having sonic image localization networks
EP0148568A1 (en) * 1983-11-22 1985-07-17 Sci-Coustics, Inc. Stereo image recovery
EP0282017A2 (en) * 1987-03-13 1988-09-14 Ohno Matsuo Stereo processing system
EP0282017A3 (en) * 1987-03-13 1989-05-24 Ohno Matsuo Stereo processing system
EP0740487A2 (en) * 1995-04-28 1996-10-30 Yamaha Corporation Stereophonic sound field expansion device
EP0740487A3 (en) * 1995-04-28 2000-09-06 Yamaha Corporation Stereophonic sound field expansion device
CN113630710A (en) * 2015-09-08 2021-11-09 苹果公司 Stereo and filter control for multi-speaker device
CN113630710B (en) * 2015-09-08 2024-05-31 苹果公司 Stereo and filter control for multi-speaker devices

Also Published As

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EP0026224A1 (en) 1981-04-08
GB2058524B (en) 1984-02-15
JPS56500477A (en) 1981-04-09
DE3041429A1 (en) 1982-02-11
EP0026224A4 (en) 1981-08-27
DE3041429C2 (en) 1992-03-12
GB2058524A (en) 1981-04-08
CA1147228A (en) 1983-05-31

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