US3721925A - Sound signal delay device - Google Patents

Abstract

A sound signal delay device having an airtight box, a plurality of partition walls forming a meandering channel in said box, a loudspeaker mounted on said box, and a microphone mounted on said box in spaced relation to said loudspeaker, whereby a sound produced by said loudspeaker is picked up as a delayed sound signal by the microphone.

Description

United States Patent Tsuchiya et al. 1March 20, 1973 [54] SOUND SIGNAL DELAY DEVICE 2,986,228 5/1961 Rettinger ......84/l.24 2,493,638 1/l950 Olson ..84/l.24 1 lnvemors= Nobol'u Tsuchlya, KanagaWa-ken; 3,160,225 12/1964 Sechrist 181/31 B Hirotake Kawakami, Tokyo, both of 3,186,509 6/1965 Dudognon ..18l/31 B Japan 2,626,992 1/1953 Holman ..333/30 R 2,826,745 3/1958 Page ..333/30 R [73] Asslgnee2 l fla Tokyo, Japan 3,434,564 3/1969 SeCl'lriSt ..181/3l B [22] Filed: May 21, 1971 Przmary Examm erHerman Karl Saalbach PP 5,823 Assistant ExaminerSaxfield Chatmon, Jr.

Attorney-Lewis H, Eslinger, Alvin Sinderbrand and [30] Foreign Application Priority Data Cums Moms & Safford May 21, 1970 Japan ..45/49633 {57] ABSTRACT A sound signal delay device having an airtight box, a [52] US. Cl. ..333/30, 84/1.24, 179/ 1.6, plurality of partition walls forming a meandering Chan 181/31 B me] in said box, a loudspeaker mounted on said box, [51] Int. Cl. ..H03n 7/30 and a microphone mounted on Said x in Spaced Fleld of Search relation to aid loudspeaker whereby a ound 333/30 produced by said loudspeaker is picked up as a delayed sound signal by the microphone. [56] References Cited UNITED STATES PATENTS 2/1964 Sutton ..l8l/3l B 4 Claims, 11 Drawing Figures PATENTEBmzoims SHEET 3 or 0 INVENTOR. NOBORl/ -1511mm y I v Air/0M5) 'PATENTEDMR201375 SHEET 0F 6 INVENTOR. 'NOB0/TU T6U6HIYA BY HUWTAKE MWAMNI PATENTEDmzomz sum 5 0F 6 INVENTOR.

T500 YA BY HIRUTAKE KAWAKAMI PATENTEUmzoms ,7 1,925

sum GDP 6 X- 3% A B 6 f 3113a D I NVEN TOR.

NUBURU T5UOHIYA BY HIIWTAKE lfAWA/WII SOUND SIGNAL DELAY DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a sound signal delay device, and more particularly to a sound signal delay device for use with stereophonic sound reproducing apparatus.

2. Description of the Prior Art Hitherto, techniques proposed for acoustic delay have included the use of such apparatus as a magnetic tape recording and reproducing apparatus, a mechanical coil spring, a reverberation room equipped with a loudspeaker and a microphone, and other apparatus for delaying a sound signal. However, these conventional means have certain defects. For one thing, the magnetic tape recording and reproducing apparatus employs rotational members, such as a drivemotor, a capstan, a pinch roller and so on, as well as supplies of expendable items, such as magnetic tape and magnetic heads. The apparatus necessitates replacement and maintenance of the parts at all times and is complicated in operation for producing a delayed sound signal. The mechanical coil spring is most widely employed, but it produces distortion in the resulting reproduced signal. The method using the reverberation room involves large-scale installations and, therefore, has limited usage. In addition, an air pipe may be employed for obtaining a delayed sound signal but, in order to obtain a long delay time, a long air pipe is required, so that this method encounters difficulty in adaptation of the air pipe to such relatively small equipment as stereophonic phonographs.

Accordingly, one object of this invention is to provide an improved sound signal delay device.

Another object of this invention is to provide a sound signal delay device which is simple in construction but provides a long delay time.

Another object of'this invention is to provide a sound signal delay device which is easy to assemble and is inexpensive.

Another object of this invention is to provide a sound signal delay device which is suitable for use with stereophonic reproducing apparatus.

Another object of this invention is to provide a sound signal delay device which readily produces many delayed sound signals. I

Another object of this invention is to provide a sound signal delay device which is provided with an airtight box capable of preventing crosstalk of a delayed sound signal with noise.

Still another object of this invention is to provide a sound signal delay device designed to be readily incorporated in a cabinet of a preamplifier or main amplifi- Other objects, features and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION The present invention comprises a sound delay device in the form of an airtight box divided by interior partitionwalls into a plurality of sections that make up a meandering channel. Sound producing means, such as a loudspeaker (or loudspeaker driver), are mounted on the airtight box to supply sound waves to the meandering channel. Sound pick-up means, which may in- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a stereophonic reproducing apparatus with a sound signal delay device;

FIG. 2 is an exploded perspective view illustrating one example of a sound signal delay device according to this invention;

FIG. 3 is a cross-sectional view taken on the plane lII--III in FIG. 2;

FIG. 4 is a fragmentary cross-sectional view showing a loudspeaker mounted on an airtight box;

FIG. 5 is a fragmentary cross-sectional view illustrating a microphone mounted on the airtight box;

FIG. 6 is a fragmentary perspective view showing a modified form of this invention;

FIG. 7 is a cross-sectional view taken on the plane VII -VII in FIG. 6;

FIGS. 8A and 8B are perspective views illustrating one example of a closing member for use with the sound signal delay device depicted in FIG. 6;

FIG. 9 is a cross-sectional view illustrating another DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention a description will be given first. of a stereophonic reproducing apparatus with an' audio signal delay system which has been proposed in our copending application entitled AUDIO SIGNAL DELAY SYSTEM," Ser. No. 138,489, filed Apr. 29, 1971. In the illustrated example the stereophonic reproducing apparatus includes a pair of input terminals 5 and 6 for connection to a signal source such as a stereophonic magnetic tape recorder, a stereophonic phonograph, or a stereophonic tuner or the like. Any of these sources produces left and right stereophonic signals L and R. The left stereophonic signal is supplied to the input terminal S and is fed through a preamplifier 7a to a left channel conductor 3a. It then goes through a left channel amplifier 7b and is applied to a left stereophonic loudspeaker SP,. The right stereophonic signal is supplied to the input terminal '6 and is fed through a Y preamplifier 8a. From there it is coupled to a right channel conductor 4a and from thence it is amplified by a right channel amplifier 8 b and is applied to a right stereophonic signals, for example, (L-R). The subtract-' ing circuit 9 may be a known type in which one of the left and right stereophonic signals L and R is phase-inverted by a transformer and is then combined with the other signal. Alternatively, one of the signals is applied to an input terminal of a one-stage amplifier and a phase-inverted output signal derived therefrom is combined with the other signal. The difference signal is fed to a delay device to produce a delayed, or reverberant, signal which will be described later on. The output side of the delay device 10 is connected to a pair of sub-loudspeakers SI and SP through a pair of amplifiers 11 and 12 respectively.

A preferred arrangement of the loudspeakers is shown in FIG. 1. With the illustrated arrangement, a listener 2 can hear left and right stereophonic sounds produced from the main loudspeakers SP and SP, which are located at the left and right corners of a listening room 1 in front of the listener. At the same time, the listener can hear reverberant sounds produced from the sub-loudspeakers SP and SP located at the left and right corners of the room 1 behind him.

In the concert hall, sounds originating from various musical instruments directly fall on the listeners ears. In addition, these sounds are reflected from the ceiling, walls, floor and the like of the concert hall and reach the listener delayed behind the direct sounds. Therefore, the listener 2 receives the sensation that individual sounds are coming from different locations, just as did the original sounds. This is quite impossible with any of conventional two-channel stereophonic reproducing systems.

In the present example the subtracting network 9 consists of amplifiers l3 and 14 respectively connected to the left and right channel conductors 3b and 4b. The amplifier 14 includes a phase inverter and the outputs of the amplifiers 13 and 14 are interconnected through resistors 16 and 17, respectively, to a common junction where the left and right stereophonic signals are' combined with each other.

The delay device 10 in the present invention is an acoustic type, which is typically illustrated in the form of an air pipe 18. Mechanically coupled to one end of the air pipe 18 on the inside thereof is a transducer, such as a small loudspeaker 19, for converting the difference signal (L-R) to a sound signal. The difference signal (L-R) from the junction 15 is supplied to the speaker 19 through an amplifier 36. The sound convetted by the speaker 19 from the difference signal (L- R) passes through the air pipe 18 toward the right in the drawing. Further, the air pipe 18 has a plurality of spaced electromechanical transducers, such as microphones, mounted thereon in predetermined spaced relation to the loudspeaker 19. In the present example, there are three microphones 20, 21 and 22. They are respectively disposed at those locations where the sound waves are delayed l5, 30 and 45 milliseconds from the time the sound is emitted by the loudspeaker at the connection point 27 is attenuated by a resistor 35 and is then applied to the amplifier 36 together with the signal derived from the connection point 15. Ac-

cordingly, the loudspeaker 19 is supplied with the composite signal in addition to the difference signal (L-R) derived from the subtracting network 9. Thus, when a signal is supplied to the loudspeaker 19, first delayed signals are picked up by the microphones 20, 21 and 22 and then applied as a composite signal to the speaker 19 to derive second delayed signals at the microphones 20 to 22. The second delayed signals are fed as a composite signal to the speaker 19 again. The above operation is repeated to derive, at the connection point 27, the composite signals of the first, second, nth delayed signals. The composite signals thus produced are reverberant signals, which are reproduced from the speakers SP and SI to provide a fairly satisfactory illusion of a sound field. In this case, the listener 2 can produce illusions of various acoustical environments by free adjustment of the volume controls 25, 30 and 31.

The sound delay device of this invention will be described in detail with reference to FIGS. 2 to 10.

In FIG. 2 reference numeral indicates, generally, the sound signal delay device, which consists of a square-shaped, open-ended box 102 and plates 104 and 105 for closing both open end portions 103a and l03b of the box 102.

The box 102 is substantially rectangular over its entire length and has, for example, two partition walls X and Y located between opposing side walls 102a and l02b at regular intervals in parallel relation to upper and bottom plates 1020 and 102d, as illustrated in the figure. In this case, both ends of the partition walls X and Y extend to the open end portions 103a and 1031;.

Thus, the box 102 is divided by the partition walls X' and Y into three cavities 106, 107 and 108.

In each of the cavities 106, 107 and 108 a plurality of partition walls are provided to form therein a plurality of channels for transmitting a sound. Since the cavities are all identical in constructions, a description will be given only of the cavity 106 for the sake of brevity. As is clearly shown in FIG. 3, for example, twelve partition walls A to L are provided between the upper plate 102:: and the partition wall X at regular intervals in parallel relation to the side walls 102a and 102b to define l3 channels a, to a by the upper plate 102 c and the partition walls X and A to L. In this case, ends a, c, e, .....k of alternate partition walls A, C, E, K extend to the one open end portion 103a of the box 102 but the other ends a, c', e, k do not extend to the other open end portion 103b, while ends b, d, f, l of the other alternate partition walls B, D, F, L do not extend to the open end portion 1030 but the other ends, b, d, f,

I extend to the open end portion l03b.

Also, in the cavities 107 and 108 13 channels B, to B and y, to 7,, are formed by partition walls similar to those A to L provided in the cavity 106. The partition wall X has an aperture 110 bored through it at a place corresponding to the ends of the channels a and [3,, on the side of the open end portion 10% for the intercommunication of the channels 0: and 3 while the partition wall Y has an aperture 112 similarly formed therein at a place corresponding to the ends of the channels and 7, on the side of the open end portion 1030 for the intercommunication of the channels 3, and 7,.

' In the illustrated example, the upper plate 102a also has an aperture 113 bored therein at a place corresponding to the end of the channel a, on the side of the open end portion 103a. A loudspeaker 141 corresponding to that indicated by reference numeral 19 in FIG. 1 is attached to the aperture 113. Further, the side wall 102b has apertures 114 and 115 formed therein at places corresponding to the ends of the channels a and 7,, on the side of the open end portion 103a, and microphones 142 and 143 corresponding to the aforementioned microphones 20 and 22 are attached to the apertures 114 and 115. Similarly, the side wall 102a has an aperture bored therein at a place corresponding to the end of the channel [3,, on the side of the open end portion 103b, and a microphone 144 corresponding to the microphone 21 is attached to the aperture, as depicted in FIG. 3.

The loudspeaker 141 is mounted by means of a rubber cover 153 on a base plate 151 having an opening 152. The base plate is fixedly mounted on the box 102 as depicted in FIG. 4. The rubber cover 153 is attached by screws 154 to the base plate 151, and an adhesive binder 155 is coated around the cover 153 to ensure that no sound escapes from the loudspeaker 141. FIG. 5 illustrates attachment of the microphone 143 to the box 102. A base plate 162 is attached by an adhesive binder to the side wall of the box 102, and a support 163 having the microphone 143 secured thereto is attached by screws 164 to the base plate 162.

Then, the plates 104 and 105 are respectively attached to the open end portions 103a and 103k of the box 102 having the channels a, to a B, to 5,, and y, to y formed therein. In this case, the plates 104 and 105 are substantially identical in shape and in size with the open end portions 103a and 103b, and rubber sheets 156 and 157 are put on those areas of the plates 104 and 105 that contact the open end portions 103a and l03b. This insures that no sound escapes from between the plates and the open end portions.

Accordingly, when the plates 104 and 105 have been attached to the open end portions 103a and 103b, the channels a, and a, intercommunicate at the. ends on the side of the plate 104 and, in a similar manner, the channels a, to a,,,, {3, to 3,, and 'y, to 7,, intercommunicate with adjacent ones and, at the same time, the channels (1,, and [3,, and B, and 7, respectively intercommunicate with each other through the apertures 110 and 112. As a result of this, the channels a, to a to 3,, B, and y, to y,,, intercommunicate with one another to provide one channel, and the loudspeaker 141 and the microphones 142, 144 and 143 are disposed along the channel at predetermined locations.

Accordingly, when the aforementioned difference signal (L-R) is supplied to the loudspeaker 141 from the subtracting network 9 in FIG. 1, for example, a sound converted by the loudspeaker 141 is fed through the aperture 113 to the channel a, and passes through the subsequent channels as indicated by the arrows in FIG. 3 and finally reaches the aperture 114 of the 13 channel a thereafter being picked up by the microphone 142 to provide a first delayed sound signal delayed by a predetermined time, for example, milliseconds behind the emission of the sound from the loudspeaker 141. Further, the sound enters the channels 3,, to B, through the aperture 110 and is picked up by the microphone 144 located outside of the last channel )8, to provide a second sound signal delayed, for example, by 30 milliseconds relative to the emission of the sound from the loudspeaker 141. Then the sound, having entered the channels 7, to 'y, is picked up by the microphone 143 disposed outside of the last channel 7,, to provide a third sound signal delayed, for example, 45 milliseconds behind the emission of the sound from the loudspeaker 141.

Although the box 102 is shown to be formed as a unitary structure, it is possible to form a plurality of boxes for each group of the channels and assemble them together into one sound delay device, still other modifications are possible. The box 102 may be formed of ABS resin (trademark), polycarbonate, acrylic resin, metal,-or the like, and the use of a hard material decreases attenuation of high-frequency sounds.

FIGS. 6 to 8 illustrate a modified form of this inven- 1 tion. In this embodiment, the end faces a, b, c, d,..... and a', b, C, d',.... of the partition walls A, B, C, L

disposed in the outer casing 202 are formed to lie in the same places as open ends 203a and 203b of the box 202. Then, closing members 227 and 228 are assembled with the box 202 to close its both open ends 203a and 203b in such a manner that the channels a, to 7,,

'intercomrnunicate with adjacent ones to provide one sound delay channel.

FIGS. 8A and 8B show such closing members 227 and 228 for closing the open ends 203a and 203k of the box 202. The closing member 227 is substantially rectangular and is open at one end 229 but closed at the other end 203. Complementary partition walls A', C, E,..... abutting with alternate ones A, C, of the box 202 and complementary partition walls X and Y abutting with those X and Y of the box 202 are provided in such a manner that their respective ends lie in the same plane. Further, a portion 231 engageable with the box 202 is formed to extend from the closing member 227. Reference numeral 210 designates an aperture for the intercommunication of the channels [3,

and 'y, as previously described. The other closing member 228 shown in FIG. 8B is identical in construction with the aforementioned member 227 except that it hascomplementary partition walls B, D, F',..... corresponding to the other alternate partition walls B; D, of the box 202 Reference numeral 212 indicates an aperture for the intercommunication of the channels 01,, and 3,, as above described. The closing members 227 and 228 are assembled with the box 202 to provide a sound delay device which has one sound channel formed therein similar to that previously described in connection with FIG. 2. An aperture 213 is formed in the closing member 227, for example, and a loudspeaker 241 is mounted on the aperture 213. Three microphones 214, 243, and 244 are mounted on the box 202. In this case, the box 202 and the closing members 227 and 228 may be formed as a unitary structure of assembled together into one structure. The box and the partition walls are formed of the same material as that of the device shown in FIG. 2.

FIG. 9 illustrates another modification of this invention, in which a sound delay box consists of a plurality of box members 302 each forming channels therein. Each box member 302 is molded as a unitary structure with its both ends 3030: and 303b closed but with, for example, its upper side opened. Accordingly, partition walls A, B, C,..... L are formed alternately to extend and not to extend at one end to either of the both ends 303a and 303b, thus providing one sound delay channel. Reference numeral 310 indicates an aperture for the intercommunication of the channels of the other box member. These box members 302 are assembled together placed one on another, for example, in three layers and then a closing plate 332 is fixedly mounted on the open end of the uppermost box member, thus providing a sound delay device.

As has been above described, in the present inven-- tion a plurality of channels are formed in an airtight box and are made to intercommunicate with one another to provide a sound delay channel, and transducer elements are mounted on the box to provide a sound delay device. Though simple in construction, the sound delay device provides delayed sound signals of relatively long delay times, as desired. Sound waves pass through a plurality of channels, so that it is possible to obtain sounds each being delayed by a time corresponding to a particular length of the channels through which the sound waves have passed. The respective desired delay times are dependent upon the locations and the number of the transducer elements and the delay times can be selected at will. Accordingly, the use of the sound delay device of this invention provides a fairly satisfactory illusion of a sound field which is unobtainable with the prior art. Further, the airtight box can be molded as a unitary structure and, hence, is easy to produce. When the sound delay device is combined with a preamplifier for stereophonic reproduction, for example, the box of the preamplifier and that of the sound delay device substantially conform with each other, so that the one can be readily housed in the other to provide for enhanced ratio of space utilization.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

We claim as our invention 1. A sound signal delay device comprising:

a. a box comprising:

1. top, bottom, side, and end external walls joined together to form an airtight parallelepiped enclosure,

. a plurality of internal partition walls within said enclosure, said partition walls comprising at least one wall substantially parallel to said side walls and located therebetween and extending from said top wall to said bottom wall and joined airtight thereto, and at least a second partition substantially parallel to said top and bottom walls and located therebetween and extending between said side walls and joined airtight thereto, selected end portions of said partitions by a length of said channel from said drive means for picking up said sound. 2. A sound signal delay device as claimed in claim 1 wherein the pick-up means comprises a plurality of microphones spaced apart from each other.

3. A sound signal delay device as claimed in claim 1 wherein the plurality of partition walls comprises a plurality of-walls parallel to said top and bottom walls and a plurality of walls parallel to said side walls.

4. A sound signal delay device as claimed in claim 1 wherein said end walls comprise acoustically absorbent material on the surface thereof facing the interior of said box.

Claims (5)

1. A sound signal delay device comprising: a. a box comprising: 1. top, bottom, side, and end external walls joined together to form an airtight parallelopiped enclosure, 2. a plurality of internal partition walls within said enclosure, said partition walls comprising at least one wall substantially parallel to said side walls and located therebetween and extending from said top wall to said bottom wall and joined airtight thereto, and at least a second partition substantially parallel to said top and bottom walls and located therebetween and extending between said side walls and joined airtight thereto, selected end portions of said partitions being spaced from said end walls to form a single meandering channel within said enclosure; b. drive means attached to said box and communicating with one end of said meandering channel to supply sound thereto; c. a cover over said drive means to prevent sound escaping therefrom outside of said box; and d. pickup means mounted on said box and separated by a length of said channel from said drive means for picking up said sound.

2. A sound signal delay device as claimed in claim 1 wherein the pick-up means comprises a plurality of microphones spaced apart from each other.

2. a plurality of internal partition walls within said enclosure, said partition walls comprising at least one wall substantially parallel to said side walls and located therebetween and extending from said top wall to said bottom wall and joined airtight thereto, and at least a second partition substantially parallel to said top and bottom walls and located therebetween and extending between said side walls and joined airtight thereto, selected end portions of said partitions being spaced from said end walls to form a single meandering channel within said enclosure; b. drive means attached to said box and communicating with one end of said meandering channel to supply sound thereto; c. a cover over said drive means to prevent sound escaping therefrom outside of said box; and d. pickup means mounted on said box and separated by a length of said channel from said drive means for picking up said sound.

3. A sound signal delay device as claimed in claim 1 wherein the plurality of partition walls comprises a plurality of walls parallel to said top and bottom walls and a plurality of walls parallel to said side walls.

4. A sound signal delay device as claimed in claim 1 wherein said end walls comprise acoustically absorbent material on the surface thereof facing the interior of said box.

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