CA1230060A - High fidelity stereophonic reproduction system - Google Patents
High fidelity stereophonic reproduction systemInfo
- Publication number
- CA1230060A CA1230060A CA000438884A CA438884A CA1230060A CA 1230060 A CA1230060 A CA 1230060A CA 000438884 A CA000438884 A CA 000438884A CA 438884 A CA438884 A CA 438884A CA 1230060 A CA1230060 A CA 1230060A
- Authority
- CA
- Canada
- Prior art keywords
- stereo
- reproduction
- high fidelity
- source device
- headphone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Abstract
ABSTRACT OF THE DISCLOSURE
A personal audio listening system to be carried by and used on the person of an individual listener which provides a high fidelity stereo sensation of being surrounded by a three dimensional field of lifelike sound. The system includes miniaturized lightweight paired stereo headphones which are an impedance and sensitivity matched to receive simultaneous mutually different output signals from a stereo amplifier which is connected to a stereo program source, such as a radio or recording playback device. The amplifier, program source and a battery are housed together in a single portable unit no larger than hand size.
A personal audio listening system to be carried by and used on the person of an individual listener which provides a high fidelity stereo sensation of being surrounded by a three dimensional field of lifelike sound. The system includes miniaturized lightweight paired stereo headphones which are an impedance and sensitivity matched to receive simultaneous mutually different output signals from a stereo amplifier which is connected to a stereo program source, such as a radio or recording playback device. The amplifier, program source and a battery are housed together in a single portable unit no larger than hand size.
Description
~2:3~6~
BACKGROUND OF TEI~ INVENTION
Vevices foL the repLoduction of music and othec sounds, either broadcast or Leeroduced from magnetic tape or disc, are increasingly popular forms of recreation and cultural development. High fidelity stereophonic systéms, in particular, have grown into a form of mass leisure and become the basis of a strongly growing audio industry.
The eresent invention relates generally to audio reproduction systems, and particularly to systems of the hiyh fidelity types, which are essentially concerned with the faithful recreation of sound events, or more exactly, with a recreation of sound sensations thaw is as close as possible to the sound sensations that a listener would have received at the elace and time of the original events, with regard to frequency range, dynamics, impulse behavior, noise, distortion (or shortly, sound quality) and, most of all, in the casé of stereophonic systems, with the local (space) and temporal phase, delay) determinants of the sound sensations. Totally, high fidelity stereophonic systems should be able to provide the whole deeth and detail that the human ear can detect in the presence of original sound events. Such a task, obviously, can only be achieved through the use of particular and partly comelex high fidelity technologies.
The invention relates further to battery-operated radio-cassette dévices of stereophonic though not high fidelity ~L~3~
type and to automobile steeeo sound systems, both of which are pLesently showing a strong gLowth in quantity as well as quality.
The invention relates finally to high fidelit~f headphone applications and to the art of binaural stereophonic reproduction in general.
PRIOR ART
High fidelity stereophonic reproduction systems prior to this invention have been made to he operated and listened to in predetermined fixed settings, usually closed rooms, in which they ace installed and connected to a power source.
Reproduction by such systems is handicapped in that it is re:;~ricted to the location at which they are set up.
Battery-operated stereophonic systems, on the other hand, have hitherto been unable to provide a realistic reeroduction of musical sounds. They lack the wide and even frequency response, timbristic detail" and spatial depth given by true high fidelity systems, which oeerate through relatively voluminous and energy consuming loudseeaker boxes and have always been connected to a power source much stronger than portable batteries.
The pooc Leproduction of prior art battery-operated stereophonic systems is aggravated at open locations, where the absence of reflected sound further weakens the sound pressure ~3~16~3 level that reaches the Listener paLticuLaLly in the lower frequency cange. The listener to such devices is far from getting a feeling of cealistic presence and illusion.
additionally, such systems are socially inconvenient in eublic elaces and wherevec they disturb other people.
Prior stereophonic eortables aLe ineffactive and disturbing, for instance, on a beach, in a garden, in the subway, or at a camping site, and incompatible with certain outdoor activities, like skiing and motorcycle riding.
Moreover, they are a constant hindrance during transeoration, being an uncomfortable commitment for at least one hand, arm, or shoulder, and interfering with bodily movements They are box-like configurations based on loudspeaker reproduction, having a speaker on each side, to be used in a resting eosition rather than during transportation. Because such systems are made, in other words, for reproduction in basically mixed (though variable) positions and inside private environments, they aLe sortable only in a very limited sense. U.S. Patent 4,081,850, issued to R. Walden in March 1978, introduces a portable tape slayer, radio and tape container, to be used during transportation: yet it is inefecti~e for this ~ureose because it erot~udes forward and backward feom the user's body, strains the shoulder, would tend to slide down from it, and would be subject to pendular movement: it is also incomeatible with stereoehonic reproduction because both speakers are at the same side of the listener; and it is, like otheL battery , .. .
~L~3~
portables, socially disturbing and not a high fidelity reproduction system.
In addition to the battery-ope~ated radio-cassette players, provided with two ox move loudseeake~s for eoctable stereophonic reproduction, which are rather cumbersome and ineffective, there have been high fidelity stereophonic tape recoLders adapted for battery operation, which are designed essentially for taee recording, and aLe equipped with only one loudspeaker, if at all, and a low voltage headphone output, included for monitoring purposes. Such instruments comply with high fidelity standards in recording, but not in battery-operated reproduction: they only provide high fidelity repLoduction in combination with a mains-powered domestic installation.
It should be noticed that prior art stereophonic reproduction systems, both of the high fidelity and of the battery portable type, aLe basically conceived, shaped, and equipped for loudspeaker reproduction - thus taking no account of the fact that binaural reproduction, through high fidelity headphones, is fax more capable of delivering an accurate reproduction of sound sensations.
Binaural ree~oduction systems are independent from room acoustics and work with much smaller masses. with full separation between the left and right ear; for these reasons they have a much better ability than loudspeakers to repcoduce the acoustic quality and space sounds. Unfortunately, most .
3~3~
pLior aLt binaural sy6tems keep the listeneL attached to a cord running between a pair oE headphones and a p.rogramme souece, which is either a fixed high fidelity system, ox a eo~table stereophonic system, away from the listene~'s body and usually played in a jesting position. Alternativaly, prior aLt binaural systems make use of a transmitter-receiver aepaLatus for the cordless link between the headphones and the p~og~amme source - but such systems still restrict the listening area, usually to the na~ow cadius of a few rooms. They also keep the control center in a se~a~ate and fixed position and they are subject to interference and noise. Earehones have been used in some potable communications devices without limitations of the uses mobility, for instance by Pando, U.S.
Patent ~,9B3,4B3 of 1976, and by Cover, U.S. Patent 2.285,083 of 1942, but such applications have been unrelated to binaural high fidelity e~inciples and to the outstanding potential of headphones and related circuitry for undistorted frequency response and accurate stereophony. In fact, they have been unrelated to the reproduction of music and of stored pLogcamme signals.
Prior at binaural systems, even of the o~en-ai~ type, also tend to isolate the listener from his acoustic environment, making it much move difficult to monitor ongoing events ox engage in conversations during ~ee~oduction than with loudspeaker systems.
Most of all, conventional stereophonic units, being 6~
essentially conceived and desi-~ned for loudspeaker ceeroduction, usually include no more than simele modifications for headehone reproduction, ratheL than active headehone amelifie~s of high fidelity tyee. because headehone reeroduction is taken as an accessory function for no more than seoradic use. High fidelity headehone ciLcuits have only been known in mains-powered and usually seeara~e units, most often designed for the operation of electrostatic headehones.
~leadehone outputs of present day amplifiers, receivers and taee recorders are usually low voltage preamplifier outeuts or simple resistor networks at loudseeaker power outputs. The design, impedance, and amplification of the active circuitry of said instruments is not adequate for high fidelity binaural reproduction, and much less for oetimal reproduction through a predetermined headehone type.
Existing high fidelity amelifiers, inasmuch as they ara not designed for a predetermined headehone type, also do not include accurate low volume comeensation because the Se!nSitiVity of the transducers is unknown, and they cannot be erovided with the necessafy equalization CiLCUits for accurate out-of-the-head simulation and for undis~oLted reeroduction of eardrum signals because the frequency reseonse of the transducer system is equally unknown. Finally, binaural reeroduction has naturally suffered fcom a lack of tactile reproduction, in particular from a lack of low frequency transmission to the listener's body.
- ;
In short:
(l) pLior art high fidelity systems are not eortable during reproduction, and are made to be used in listening rooms;
BACKGROUND OF TEI~ INVENTION
Vevices foL the repLoduction of music and othec sounds, either broadcast or Leeroduced from magnetic tape or disc, are increasingly popular forms of recreation and cultural development. High fidelity stereophonic systéms, in particular, have grown into a form of mass leisure and become the basis of a strongly growing audio industry.
The eresent invention relates generally to audio reproduction systems, and particularly to systems of the hiyh fidelity types, which are essentially concerned with the faithful recreation of sound events, or more exactly, with a recreation of sound sensations thaw is as close as possible to the sound sensations that a listener would have received at the elace and time of the original events, with regard to frequency range, dynamics, impulse behavior, noise, distortion (or shortly, sound quality) and, most of all, in the casé of stereophonic systems, with the local (space) and temporal phase, delay) determinants of the sound sensations. Totally, high fidelity stereophonic systems should be able to provide the whole deeth and detail that the human ear can detect in the presence of original sound events. Such a task, obviously, can only be achieved through the use of particular and partly comelex high fidelity technologies.
The invention relates further to battery-operated radio-cassette dévices of stereophonic though not high fidelity ~L~3~
type and to automobile steeeo sound systems, both of which are pLesently showing a strong gLowth in quantity as well as quality.
The invention relates finally to high fidelit~f headphone applications and to the art of binaural stereophonic reproduction in general.
PRIOR ART
High fidelity stereophonic reproduction systems prior to this invention have been made to he operated and listened to in predetermined fixed settings, usually closed rooms, in which they ace installed and connected to a power source.
Reproduction by such systems is handicapped in that it is re:;~ricted to the location at which they are set up.
Battery-operated stereophonic systems, on the other hand, have hitherto been unable to provide a realistic reeroduction of musical sounds. They lack the wide and even frequency response, timbristic detail" and spatial depth given by true high fidelity systems, which oeerate through relatively voluminous and energy consuming loudseeaker boxes and have always been connected to a power source much stronger than portable batteries.
The pooc Leproduction of prior art battery-operated stereophonic systems is aggravated at open locations, where the absence of reflected sound further weakens the sound pressure ~3~16~3 level that reaches the Listener paLticuLaLly in the lower frequency cange. The listener to such devices is far from getting a feeling of cealistic presence and illusion.
additionally, such systems are socially inconvenient in eublic elaces and wherevec they disturb other people.
Prior stereophonic eortables aLe ineffactive and disturbing, for instance, on a beach, in a garden, in the subway, or at a camping site, and incompatible with certain outdoor activities, like skiing and motorcycle riding.
Moreover, they are a constant hindrance during transeoration, being an uncomfortable commitment for at least one hand, arm, or shoulder, and interfering with bodily movements They are box-like configurations based on loudspeaker reproduction, having a speaker on each side, to be used in a resting eosition rather than during transportation. Because such systems are made, in other words, for reproduction in basically mixed (though variable) positions and inside private environments, they aLe sortable only in a very limited sense. U.S. Patent 4,081,850, issued to R. Walden in March 1978, introduces a portable tape slayer, radio and tape container, to be used during transportation: yet it is inefecti~e for this ~ureose because it erot~udes forward and backward feom the user's body, strains the shoulder, would tend to slide down from it, and would be subject to pendular movement: it is also incomeatible with stereoehonic reproduction because both speakers are at the same side of the listener; and it is, like otheL battery , .. .
~L~3~
portables, socially disturbing and not a high fidelity reproduction system.
In addition to the battery-ope~ated radio-cassette players, provided with two ox move loudseeake~s for eoctable stereophonic reproduction, which are rather cumbersome and ineffective, there have been high fidelity stereophonic tape recoLders adapted for battery operation, which are designed essentially for taee recording, and aLe equipped with only one loudspeaker, if at all, and a low voltage headphone output, included for monitoring purposes. Such instruments comply with high fidelity standards in recording, but not in battery-operated reproduction: they only provide high fidelity repLoduction in combination with a mains-powered domestic installation.
It should be noticed that prior art stereophonic reproduction systems, both of the high fidelity and of the battery portable type, aLe basically conceived, shaped, and equipped for loudspeaker reproduction - thus taking no account of the fact that binaural reproduction, through high fidelity headphones, is fax more capable of delivering an accurate reproduction of sound sensations.
Binaural ree~oduction systems are independent from room acoustics and work with much smaller masses. with full separation between the left and right ear; for these reasons they have a much better ability than loudspeakers to repcoduce the acoustic quality and space sounds. Unfortunately, most .
3~3~
pLior aLt binaural sy6tems keep the listeneL attached to a cord running between a pair oE headphones and a p.rogramme souece, which is either a fixed high fidelity system, ox a eo~table stereophonic system, away from the listene~'s body and usually played in a jesting position. Alternativaly, prior aLt binaural systems make use of a transmitter-receiver aepaLatus for the cordless link between the headphones and the p~og~amme source - but such systems still restrict the listening area, usually to the na~ow cadius of a few rooms. They also keep the control center in a se~a~ate and fixed position and they are subject to interference and noise. Earehones have been used in some potable communications devices without limitations of the uses mobility, for instance by Pando, U.S.
Patent ~,9B3,4B3 of 1976, and by Cover, U.S. Patent 2.285,083 of 1942, but such applications have been unrelated to binaural high fidelity e~inciples and to the outstanding potential of headphones and related circuitry for undistorted frequency response and accurate stereophony. In fact, they have been unrelated to the reproduction of music and of stored pLogcamme signals.
Prior at binaural systems, even of the o~en-ai~ type, also tend to isolate the listener from his acoustic environment, making it much move difficult to monitor ongoing events ox engage in conversations during ~ee~oduction than with loudspeaker systems.
Most of all, conventional stereophonic units, being 6~
essentially conceived and desi-~ned for loudspeaker ceeroduction, usually include no more than simele modifications for headehone reproduction, ratheL than active headehone amelifie~s of high fidelity tyee. because headehone reeroduction is taken as an accessory function for no more than seoradic use. High fidelity headehone ciLcuits have only been known in mains-powered and usually seeara~e units, most often designed for the operation of electrostatic headehones.
~leadehone outputs of present day amplifiers, receivers and taee recorders are usually low voltage preamplifier outeuts or simple resistor networks at loudseeaker power outputs. The design, impedance, and amplification of the active circuitry of said instruments is not adequate for high fidelity binaural reproduction, and much less for oetimal reproduction through a predetermined headehone type.
Existing high fidelity amelifiers, inasmuch as they ara not designed for a predetermined headehone type, also do not include accurate low volume comeensation because the Se!nSitiVity of the transducers is unknown, and they cannot be erovided with the necessafy equalization CiLCUits for accurate out-of-the-head simulation and for undis~oLted reeroduction of eardrum signals because the frequency reseonse of the transducer system is equally unknown. Finally, binaural reeroduction has naturally suffered fcom a lack of tactile reproduction, in particular from a lack of low frequency transmission to the listener's body.
- ;
In short:
(l) pLior art high fidelity systems are not eortable during reproduction, and are made to be used in listening rooms;
(2) pLior art battery-operated stereophonic systems do not provide high fidelity LepLoduction and are eortable only in very limited sense;
(3) erior aLt binaural eeproduction systems, which comprise headphone transducers in connection with (l) and (2) above, also limit the listener's mobility, most often by attaching him to a cord, and do not usually include matching circuitry for binaural high fidelity.
No effective solution for the high fi.delity reproduction of music and other sound sensations has been of~Eersd heretofore without implying a simultaneous impèdiment 20 to the listener's freedom of movement and choice of environmsnts.
It should be noticed that such a situation has persisted in spite of strong and growing trends toward:
(a) high fidelity systems, (b) miniaturized reproduction devices, (c) portable stereophonic reproduction, {d) automobile hi-fi stereo systems, . I, ,~
~L23~ fix (e) potable hi-fi stereo Leco~ding systems, (f) headehone ceLLoduction.
Because of the lack of an effective solution for eortable high fidelity ree~oduction, the peculiar sensation of listening to a realistic, three-dimensional reproduction of music undec the open sky, as well as in a variety of other situations and activities. has been generally unavailable to this date.
The applicant is aware of:-10 (1) U.S. Patent 4,081,850: poLtable tape player and tape container, Richard Walden, 1978.
(2) U.S. Patent 3,983,483: communications davice arranged to be woLn in intimate contact with the body of a user, Donald Pando, 1976.
15 (3~ U.S. Patent 2,285,083: two-way radio garment, Be~key Cover, 1942.
No effective solution for the high fi.delity reproduction of music and other sound sensations has been of~Eersd heretofore without implying a simultaneous impèdiment 20 to the listener's freedom of movement and choice of environmsnts.
It should be noticed that such a situation has persisted in spite of strong and growing trends toward:
(a) high fidelity systems, (b) miniaturized reproduction devices, (c) portable stereophonic reproduction, {d) automobile hi-fi stereo systems, . I, ,~
~L23~ fix (e) potable hi-fi stereo Leco~ding systems, (f) headehone ceLLoduction.
Because of the lack of an effective solution for eortable high fidelity ree~oduction, the peculiar sensation of listening to a realistic, three-dimensional reproduction of music undec the open sky, as well as in a variety of other situations and activities. has been generally unavailable to this date.
The applicant is aware of:-10 (1) U.S. Patent 4,081,850: poLtable tape player and tape container, Richard Walden, 1978.
(2) U.S. Patent 3,983,483: communications davice arranged to be woLn in intimate contact with the body of a user, Donald Pando, 1976.
15 (3~ U.S. Patent 2,285,083: two-way radio garment, Be~key Cover, 1942.
(4) U.S. Patent 3,920,904: method and aeea~atus for imparting to headehones the sound reproduction characteristic to loudspeakers, InventoLs: Jens Blauert & Peter Laws, assignee: Eugen Beye~
Elekt~otechnische Fabrik, Heilbronn, German Federal Republic.
Elekt~otechnische Fabrik, Heilbronn, German Federal Republic.
(5) GBM 7,509,223 (German Federal Republic): anordnung our fixierung von auBenohr-MeBmnikrophonen am koef, Eugen 2~ Beyer ~lektrotechnische Fab~ik.
(6) U.S. Patent 3,962,543: method and arrangement for I.
~3~
cont~ollinq the acoustic ouput of earphones in response to rotations ox listener's head, Inventors:
Jens Blauert. Georg Boerger, Peter Laws, Assignee:
Even Beyec Elektrotechnische F'abrik.
OBJECTS OF THE INVENTION
The main and essential object of the present invention is to erovide a stereophonic reproduction system providing high fidelity reproduction together with a practically unlimited mobility for the listener.
another object is to provide a system ox the type described above allowing for pLivate listening without acoustic isolation of the listener in any degree, unless wanted.
~nothec object is to provide a system of the type described above allowing for individualized reproduction of a recorded programme without restrictions to the numbeL of llsteners.
another object is to provide a system of the type described above allowing for out-o~-the-head location of reproduced sound sensations and or high precision s~ereop~onic reproduction from probe microphone recordings of eardrum or earchannel signals.
another object is to provide a system of the type described above allowing for the simulation of room acoustics.
~L~3~
notheL ohJect is Jo provide a system of the type desceibed above including means to offset the rotational shift of sound reproduction caused by the listener's head movements.
Another object is to erovide a system of the type described above allowing for undistorted frequency response at noLmal and high volumes and automatic loudness compensation at low volumes.
Another object is to provide a system of the type described above allowing for tactile bass reeroduction at certain points of the listener's body.
Another object is to provide a system of the type described above allowing for live amplification of sound events as well as for the mixing and simultaneous amplification of different signal sources.
Another object is to pLovide a system of the type described above, allowing for sound reproduction of greater quality and realism than conventional high fidelity system operating with fixed loudspeaker installations.
nother object is to provide a system of the type described above, offering high quality audio reproduction at considerably lower cost than conventional high fidelity systems operating through loudspeakers which use heavy power amplifiers.
nother object is to provide a battery-operated stereoehonic reproduction system that is more portable than previous stereophonic portables and causes no social disturbance, yet is able to play at louder volumes and convey a ~'~3~
strongeL sense of stereophonic space and cealism.
nother object is to provide a system of the type described above, allowing for high fi.delity Leeroduction inside mobile units such as a car, while also allowing for the same kind of Leeroduction outside and independently of such units.
AnotheL object is to provide a system of the type described above, allowing for highly realistic yet unencumbering stereoehonic reproduction in an un].imited number of situations, activities, and motion states, such as walking, sitting, sunning, dancing, skiing, mountain climbing, camping, cooking, lawn mowing, working at a machine or at a desk, and riding, driving or being transeorted by a vehicle like a train, bus, motorcycle, bicycle, boat, airplane, hangglider, etc.
Another object is to provide a system of the type described above, allowing the listener to experience the peculiar audiovisual stimulation that results from the association of musical sequences with a flow of changing images and environments as perceived in the cinema or by a person in motion.
another object is to provide a cordless headphone system in which the cord attachment of the listener is eliminated by securing a suitably conceived high fidelity source on the listener himself, thus attaining unrestricted mobility in an unlimited listening area.
Another object is to provide a perfect binaural reproduction system, avoiding the major handicaps of previous ~3~
headphone aLLangements, such as physical discomfort, acoustic isolation, in-the-head location, lack o tactile bass sensations, and ~est~iction of the number of listenecs.
Another object is to provide a system of the type desribed above including means that allow for electronic sound synthesizing.
Another object is to pcovide a system of the type described above, comprising means to pick up some of the listener's physiological pacameters and convert them into audio signals suitable foL biofeedback training.
Another object is to povide a system of the type desccibed above, which is at the same time a ready-to-use recording and mixing system, with microphones and headphones always in elace for the instant recording and monitoring of live sound events.
nother object is to provide a system of the tyee described above, allowing for the stereophonic recording of live sound events in synchronization with the simultaneous recording of live image& of the same vents through cinematographic or electronic means.
SUMMARY OF ~HE_INVENTI~ON
The present invention contemplates a stereophonic repcoduction system that is able to provide high fidelity reproduction of sounds while allowing for a practically 3~36~
unlimited mobility of the Listener. The invention eliminates the need for a fixed installation of high fidelity ceeLoduction systems through the combination and mutual adaptation of seveLal electroacoustical devices. adequately miniaturized and shaped to be used on the person of the listene{. The eresent ste{eophonic system is able to provide sound rep{oduction as accurate as the very best arrangements of previous high fidelity art, yet it does not {est{ict the listenec to a listening aeea noc interfe{e with his bodily movements. The invention is superior to all previous high fidelity arrangements in that it combines the advantage of binaural stereoehony with those of loudseeaker reproduction. It is able to avoid, in other words, all the majo{ shortcomings of previous stereophonic arrangements functioning with loudspeaker or headphone reproduction, as indicated in earenthesis below, and which aLe:
(a) {estriction of the reproduction to a listening room (loudspeakers) or to a listening area (cordless headphone systems), 20 (by attachment of the listener to a cord (ordinary headphone systems), (c) interference of listening room acoustics with frequency cesponse and time-delay characteristics of the reproduction (loudspeakers), 25 (d) in-the-head location and front/back inversion of {eproduced sound events (headphones), . .
3~6~
(e) disturbance of unwanted listeners loudspeakers), (f) acoustic isolation of the listener (headphones), (g) lack of accurate stereophorly - including a ].ack of veLtical positionin-J, of proximity gradations, of detail in left/tight positioning and, with the usual two channels, also of front/back distribution of sound events (loudspeakers), (h) absence of tactile bass transmission to the listener's body (headphone reproduction).
The invention comerises at least and essentially a high fidelity stereoehonic playback device such as a magnetic tape player, two signal amelifiers designed fox binaural high fidelity reeroduction and optimal reseonse through a given headphone type, high fidelity headehones with lightweight o~en-air characteristics having electrical specifications which match the amplifier output in terms of impedance and sensitivity and a battery power supply.
In the ereferred embodiment the invention provides a personal stereo sound system, to be carried and used on the person of at least one individual listener, comprising the combination of (i) a miniaturized erogram source device arranged to produce simultaneous mutually different steLeo program outeut signals; (ii) miniaturized stereo signal amplifier means, imeedance ma-tched to, and arranged to receive the stereo output signals from the source device; (iii) miniaturized lightweight paired stereo headehone maans, ~'~3~6~
physically Lemote prom the source device, impedance and sensitivity matched to and aLranged to receive separately, one signal for each phone, the output signals of the amplifier means through separate cable means; (iv) volume adjusting means for the signals received by the headphone means; and (v) power source means come~ising a battery electcically connected to the amplifier means and to the source device and housed together with the amplifiec means and source device in a single portable unit no larger than hand size.
In its most effective and referred embodiment the invention further includes preamplifying control and switching circuitry comprising balance and tone controls, a high fidelity FM broadcast ceceiver and stereo decoder, a radio antenna fixed on or built into a belt, a set of at least two miniature microphones with microphone amplifiers and stereophonic mixing circuitry for the simultaneous reproduction of progLam materials and environmental sounds, a headphone equalize for adequate frequency response, phase and frequency compensation circuitry for the simulation of loudspeaker reproduction by means of headphones and for the undistorted reproduction of eardrum signals, as recorded with binaural erobe microphones.
two ways of achieving out-of-the-head location of sound events, a stereophonic transmitter with corresponding antenna for the cordless connection of additional headphone listeners, provided with suitable stereophQnic receiver/am~lifiers and antennas of their own, contact transducers, also known as body transducers, , ,.
~3~
foc the tactile repLoduction of low bass vibrations at various body spots, loudness CiLCUitCy foL the automatic compensation of subjective ~Lequency losses at low volume settings thLough a given tLansducer type, tone control circuitry for the timbristic corLection of ~cogram mateLials, an automatic cut-off OL limiting circuit to protect the listener's ears from harmful headphone amelitudes and shock absorbing s~ring/mass suspension systems with low-~ass damping characteris-tics for the suspension of the various re~Eoduction devices to protect their high fidelity peLformance feom the interference of shocks and vibrations tLansmitted from the user's body.
These and other devices are incoLpo~ated jointly or alternatively into the most effective and desirable embodiment of the resent binaural high fidelity system inasmuch as the reproduction quality and flexibility which they provide is made compatible with a comfortable weight and adequate cost through the use of integrated circuit technology and miniaturization techniques. Under this condition the preferred embodiment of the disclosed system may further include time delay circuitLy for the simulation of room acoustics, and a small size sensor of rotational head movements to be fixed into the headband of the user's headphones with corLesponding circuitry in order to allow foL the simulation of an immobile listeneL-inde~endent soundspace in spite of the user's head movements. Thece may also be included an acoustic cancellation circuit allowing, if wanted, for the cancellation of environmental noise as ~Z3~1~)fi~
perceived through the open-ai~ head~ones, by using mic~o~hone signals of invected ehase. Obviously, and deeending on the state of recording and broadcasting technology at the time of construction, the preferred embodiment of the eresent system may also include various circuits for noise reduction and dynamic exeansion of audio signals to assure the most natural sound reproduction of tape and Ladio programs.
In the ereferred embodiment and in accordance with the basic concept of the pLesent invention all parts and assemblies are miniaturized and integrated to the utmost. They aLe grouped in removable modules which are shaped and distributed for maximal comfoLt. The headphones are of a foldable or collapsible type and may be stored. The batteries are of accumulator type and placed in removable containers to be recharged independently from the system, and the outwit may include further containers or support structure for the storage of memory devices like magnetic tape cassettes. Comfort of use is further achieved through the inclusion of automatic erogram searching devices for the selection of recorded pieces or of radio stations, and of touch buttons and electronic read-outs for easy control.
F'inally it should be noted that the present system can be supplemented in its essential functions of portable high fidelity reeroduction by other functions provided by additional devices.
The present invention makes high grade reproduction of ~230~6~
sound sens~ti~nfi dvail~ble outside of mixed listening rooms, and genecally in an unlimited number of situations and activities, without restLicting the listening area or physical comfort of the listener.
the solution is found in a combination of:
Al) a compact high fidelity stereophonic progLam source including a playback device, (Z) a pair of high fidelity headehone amplifiers adapted for battery opecation and optimal reeroduction through a given type of headphones, (3) lightweight and open high fidelity headphones, (4) miniatucization and anatomic design of said earts, allowing for (5) incorporation of small controls provided with wiring and (6) a battery powec supply.
The solution is further improved by the inclusion of:
~3~
cont~ollinq the acoustic ouput of earphones in response to rotations ox listener's head, Inventors:
Jens Blauert. Georg Boerger, Peter Laws, Assignee:
Even Beyec Elektrotechnische F'abrik.
OBJECTS OF THE INVENTION
The main and essential object of the present invention is to erovide a stereophonic reproduction system providing high fidelity reproduction together with a practically unlimited mobility for the listener.
another object is to provide a system ox the type described above allowing for pLivate listening without acoustic isolation of the listener in any degree, unless wanted.
~nothec object is to provide a system of the type described above allowing for individualized reproduction of a recorded programme without restrictions to the numbeL of llsteners.
another object is to provide a system of the type described above allowing for out-o~-the-head location of reproduced sound sensations and or high precision s~ereop~onic reproduction from probe microphone recordings of eardrum or earchannel signals.
another object is to provide a system of the type described above allowing for the simulation of room acoustics.
~L~3~
notheL ohJect is Jo provide a system of the type desceibed above including means to offset the rotational shift of sound reproduction caused by the listener's head movements.
Another object is to erovide a system of the type described above allowing for undistorted frequency response at noLmal and high volumes and automatic loudness compensation at low volumes.
Another object is to provide a system of the type described above allowing for tactile bass reeroduction at certain points of the listener's body.
Another object is to provide a system of the type described above allowing for live amplification of sound events as well as for the mixing and simultaneous amplification of different signal sources.
Another object is to pLovide a system of the type described above, allowing for sound reproduction of greater quality and realism than conventional high fidelity system operating with fixed loudspeaker installations.
nother object is to provide a system of the type described above, offering high quality audio reproduction at considerably lower cost than conventional high fidelity systems operating through loudspeakers which use heavy power amplifiers.
nother object is to provide a battery-operated stereoehonic reproduction system that is more portable than previous stereophonic portables and causes no social disturbance, yet is able to play at louder volumes and convey a ~'~3~
strongeL sense of stereophonic space and cealism.
nother object is to provide a system of the type described above, allowing for high fi.delity Leeroduction inside mobile units such as a car, while also allowing for the same kind of Leeroduction outside and independently of such units.
AnotheL object is to provide a system of the type described above, allowing for highly realistic yet unencumbering stereoehonic reproduction in an un].imited number of situations, activities, and motion states, such as walking, sitting, sunning, dancing, skiing, mountain climbing, camping, cooking, lawn mowing, working at a machine or at a desk, and riding, driving or being transeorted by a vehicle like a train, bus, motorcycle, bicycle, boat, airplane, hangglider, etc.
Another object is to provide a system of the type described above, allowing the listener to experience the peculiar audiovisual stimulation that results from the association of musical sequences with a flow of changing images and environments as perceived in the cinema or by a person in motion.
another object is to provide a cordless headphone system in which the cord attachment of the listener is eliminated by securing a suitably conceived high fidelity source on the listener himself, thus attaining unrestricted mobility in an unlimited listening area.
Another object is to provide a perfect binaural reproduction system, avoiding the major handicaps of previous ~3~
headphone aLLangements, such as physical discomfort, acoustic isolation, in-the-head location, lack o tactile bass sensations, and ~est~iction of the number of listenecs.
Another object is to provide a system of the type desribed above including means that allow for electronic sound synthesizing.
Another object is to pcovide a system of the type described above, comprising means to pick up some of the listener's physiological pacameters and convert them into audio signals suitable foL biofeedback training.
Another object is to povide a system of the type desccibed above, which is at the same time a ready-to-use recording and mixing system, with microphones and headphones always in elace for the instant recording and monitoring of live sound events.
nother object is to provide a system of the tyee described above, allowing for the stereophonic recording of live sound events in synchronization with the simultaneous recording of live image& of the same vents through cinematographic or electronic means.
SUMMARY OF ~HE_INVENTI~ON
The present invention contemplates a stereophonic repcoduction system that is able to provide high fidelity reproduction of sounds while allowing for a practically 3~36~
unlimited mobility of the Listener. The invention eliminates the need for a fixed installation of high fidelity ceeLoduction systems through the combination and mutual adaptation of seveLal electroacoustical devices. adequately miniaturized and shaped to be used on the person of the listene{. The eresent ste{eophonic system is able to provide sound rep{oduction as accurate as the very best arrangements of previous high fidelity art, yet it does not {est{ict the listenec to a listening aeea noc interfe{e with his bodily movements. The invention is superior to all previous high fidelity arrangements in that it combines the advantage of binaural stereoehony with those of loudseeaker reproduction. It is able to avoid, in other words, all the majo{ shortcomings of previous stereophonic arrangements functioning with loudspeaker or headphone reproduction, as indicated in earenthesis below, and which aLe:
(a) {estriction of the reproduction to a listening room (loudspeakers) or to a listening area (cordless headphone systems), 20 (by attachment of the listener to a cord (ordinary headphone systems), (c) interference of listening room acoustics with frequency cesponse and time-delay characteristics of the reproduction (loudspeakers), 25 (d) in-the-head location and front/back inversion of {eproduced sound events (headphones), . .
3~6~
(e) disturbance of unwanted listeners loudspeakers), (f) acoustic isolation of the listener (headphones), (g) lack of accurate stereophorly - including a ].ack of veLtical positionin-J, of proximity gradations, of detail in left/tight positioning and, with the usual two channels, also of front/back distribution of sound events (loudspeakers), (h) absence of tactile bass transmission to the listener's body (headphone reproduction).
The invention comerises at least and essentially a high fidelity stereoehonic playback device such as a magnetic tape player, two signal amelifiers designed fox binaural high fidelity reeroduction and optimal reseonse through a given headphone type, high fidelity headehones with lightweight o~en-air characteristics having electrical specifications which match the amplifier output in terms of impedance and sensitivity and a battery power supply.
In the ereferred embodiment the invention provides a personal stereo sound system, to be carried and used on the person of at least one individual listener, comprising the combination of (i) a miniaturized erogram source device arranged to produce simultaneous mutually different steLeo program outeut signals; (ii) miniaturized stereo signal amplifier means, imeedance ma-tched to, and arranged to receive the stereo output signals from the source device; (iii) miniaturized lightweight paired stereo headehone maans, ~'~3~6~
physically Lemote prom the source device, impedance and sensitivity matched to and aLranged to receive separately, one signal for each phone, the output signals of the amplifier means through separate cable means; (iv) volume adjusting means for the signals received by the headphone means; and (v) power source means come~ising a battery electcically connected to the amplifier means and to the source device and housed together with the amplifiec means and source device in a single portable unit no larger than hand size.
In its most effective and referred embodiment the invention further includes preamplifying control and switching circuitry comprising balance and tone controls, a high fidelity FM broadcast ceceiver and stereo decoder, a radio antenna fixed on or built into a belt, a set of at least two miniature microphones with microphone amplifiers and stereophonic mixing circuitry for the simultaneous reproduction of progLam materials and environmental sounds, a headphone equalize for adequate frequency response, phase and frequency compensation circuitry for the simulation of loudspeaker reproduction by means of headphones and for the undistorted reproduction of eardrum signals, as recorded with binaural erobe microphones.
two ways of achieving out-of-the-head location of sound events, a stereophonic transmitter with corresponding antenna for the cordless connection of additional headphone listeners, provided with suitable stereophQnic receiver/am~lifiers and antennas of their own, contact transducers, also known as body transducers, , ,.
~3~
foc the tactile repLoduction of low bass vibrations at various body spots, loudness CiLCUitCy foL the automatic compensation of subjective ~Lequency losses at low volume settings thLough a given tLansducer type, tone control circuitry for the timbristic corLection of ~cogram mateLials, an automatic cut-off OL limiting circuit to protect the listener's ears from harmful headphone amelitudes and shock absorbing s~ring/mass suspension systems with low-~ass damping characteris-tics for the suspension of the various re~Eoduction devices to protect their high fidelity peLformance feom the interference of shocks and vibrations tLansmitted from the user's body.
These and other devices are incoLpo~ated jointly or alternatively into the most effective and desirable embodiment of the resent binaural high fidelity system inasmuch as the reproduction quality and flexibility which they provide is made compatible with a comfortable weight and adequate cost through the use of integrated circuit technology and miniaturization techniques. Under this condition the preferred embodiment of the disclosed system may further include time delay circuitLy for the simulation of room acoustics, and a small size sensor of rotational head movements to be fixed into the headband of the user's headphones with corLesponding circuitry in order to allow foL the simulation of an immobile listeneL-inde~endent soundspace in spite of the user's head movements. Thece may also be included an acoustic cancellation circuit allowing, if wanted, for the cancellation of environmental noise as ~Z3~1~)fi~
perceived through the open-ai~ head~ones, by using mic~o~hone signals of invected ehase. Obviously, and deeending on the state of recording and broadcasting technology at the time of construction, the preferred embodiment of the eresent system may also include various circuits for noise reduction and dynamic exeansion of audio signals to assure the most natural sound reproduction of tape and Ladio programs.
In the ereferred embodiment and in accordance with the basic concept of the pLesent invention all parts and assemblies are miniaturized and integrated to the utmost. They aLe grouped in removable modules which are shaped and distributed for maximal comfoLt. The headphones are of a foldable or collapsible type and may be stored. The batteries are of accumulator type and placed in removable containers to be recharged independently from the system, and the outwit may include further containers or support structure for the storage of memory devices like magnetic tape cassettes. Comfort of use is further achieved through the inclusion of automatic erogram searching devices for the selection of recorded pieces or of radio stations, and of touch buttons and electronic read-outs for easy control.
F'inally it should be noted that the present system can be supplemented in its essential functions of portable high fidelity reeroduction by other functions provided by additional devices.
The present invention makes high grade reproduction of ~230~6~
sound sens~ti~nfi dvail~ble outside of mixed listening rooms, and genecally in an unlimited number of situations and activities, without restLicting the listening area or physical comfort of the listener.
the solution is found in a combination of:
Al) a compact high fidelity stereophonic progLam source including a playback device, (Z) a pair of high fidelity headehone amplifiers adapted for battery opecation and optimal reeroduction through a given type of headphones, (3) lightweight and open high fidelity headphones, (4) miniatucization and anatomic design of said earts, allowing for (5) incorporation of small controls provided with wiring and (6) a battery powec supply.
The solution is further improved by the inclusion of:
(7) a pair of microphones and microphone amplifiers, ~8) a mixec connected for instant reproduction of live events together with the ~rogLam soucce, ~9~ binaural equalization circuitcy for the manipulation and compensation of the quality, temporal, and local determinants of sound sensations, (lO) a set of bass range contact transducers, ill) a sterophonic high ~ideli~y transmitter for the coLdless connection of additional headphones, s,, ~23~
(12) a s~ring/mass suseension system having damping characteristics that isolate the eerformance of the high fidelity devices from the interference of mechanical vibrations.
The system is able to eroject three-dimensional acoustic environments and sound events in high definition for a listener who is himself unrestricted in his mobility and choice of physical environments, thereby creating a new and unique acoustic and audiovisual experience.
BRIEF DESCRIPTION OF THE DRAWINGS
The functional and constructive characteristics of the present invention will become more apparent from the following description, in which reference is jade to the acçompanying drawings, which illustrate an exemplificative and not limitative embodiment of the invention for high fidelity stereophonic reproduction, and wherein -Fig. 1 is a front view of a system, equipped with devices for high fidelity stereophonic reproduction:
Fig. 2 is a back view of the same system:
Fig. 3 is a view of a supporting and interconnective Rand without any of the casings and respective devices:
Fig. 4 illustrates an example of application of the present invention.
The system for high fidelity stereophonic reproduction ~3~6~
includes four main paLts:
(i) a playback device 1, (ii) a pair of high fidelity headphone amplifiers, (iii) a pair of high fidelity headphones (or earphones) 3, tiv) one or more battery casings 4 (containing batteries 5).
In the referred embodiment other parts are equally important:
a pair of miniature microphones 7, a eair of microphone amplifiers, four-channel mixing circuitry, a high fidelity broadcast FM receiver, an FM stereo decoder The following accessory elements complete the basic arrangement:
a band and a buckle 8, an extensible eortion 9, inte~connective wiring -Eor signal and power transmission lO, an antenna 11.
The invention may further comprise:
a number oE padding cushions 12, a support structure or casing 13 for magnetic tape cassettes 14, -- ZO --~3~
another structure 15 to SUppoLt the headphones 3 in collapsed foLm, a elurality of contact tcansduce~s 16, spring/mass damping mechanics for the suspension of the playback device and various circuits.
Naturally, it is understood that the instant system be so designed that all its circuits and devices are miniaturized to the utmost and may be built into the band 6 in a compact and integrative way, and that they may be contained in any number of housings, variously distributed alongside the band.
Referring now to its constituent parts in more detail, the system for high fidelity stereophonic reproduction compzises a high Eidelity playback device 1 effective to pick up stereoehonic audio signals from magnetic tape cassettes 14 OL other carrier of recorded audio information memory devices), and supply them to an output end, which connects to a pair of high fidelity headphone amplifiers 2 by means of wire connections lO. arranged betwean two layers of the supporting band 6.
The fixation of the devices 1, 2 and other circuitry, in their respective casings may be obtained with the inclusion of spring~mass damping systems located between the casings and the devices contained therein, or between the coupling pats of all other parts of the devices 1 and 2, or integrated to the li, ~30~6~
coupling warts located on the band 6, wherein said dameing systems have low-pass characteristics that adequately isola-te the reproduction devices from shocks and vibrations, above a predetermined frequency, originating from the user's bodily movements.
The playback device 1, the headphone amplifieLs 2 and all other circuitry that may optionally be included and is referred Jo below, are adapted for battery operation. The hatteries 5, preferably of rechargeable type, are provided in sufficient numbec and size foc the operation of the various devices of the system durinq a useful length of time, and are located inside of one or more appropriate casings 4, equipeed with contact ends and supplying vower to the devices through wiring 10, running along or inside the band 6. alternatively, said batteries may be directly housed inside the casings of the devices 1 and 2.
n ac/dc voltage converter may also be included to increase the voltage of the power supply, if the circuitry of the system is designed to operate at relatively higher voltage while using only a small number of batteries.
The playback device 1 may include its own preamplifying stave, adapted to the characteristics of the eick-u~ head and to one or several types of signal carrier (memory device), like a cassette type a miniature disc, or a hologram, which are to be introduced into the elayback device 1, preferably by means of a slot-load mechanism. The partially - ~2 -, .
., .
~351~6~
amplified ste~eoLhonic signal is delivered, through appLo~riate output ends, to the wiving lO, which supplies the same signal to the input ends of the headphone amplifiecs 2. The elayback device 1 may be provided with all capabilities of recent reeroduction technology, like automatic program seacching, noise reduction circuitry, digital read-outs, etc.
The headehone amplifiers 2 may include a preamplifying stage comprising volume, balance, tone control and switching weans, together with a main amplifying stage. The amplifier is provided with one or preferably several headphone outputs, to which one OL more pairs of headphones 3 can be connected.
The headphones 3 of the lightweight and high fidelity characteristics, are preferably of the "open air" nonisolating type and may include a headband sup~oLt OL be directly fixed to the ears. The headband support is preferably formed with a foLdable or collapsible structure.
A short range, high quality stereophGnic transmitter, either contained in the same casing of the headphone amplifieLs 2, or in a separate casing, may be connected to the preamplifier output to provide for the cordless connection of an unlimited number of headphone pairs 3, each provided with its own pair of receivers and reception antennas, stereoehonic amplifier, and power supply. The stereophonic transmitter is also connected to an antenna for signal transmission.
The system for high fidelity stereophonic reproduction may also include a elurality ox contact transducers 16 ~3~
dist~ihuted alon-Jside the innec face of the suppoLtin-~ band 6, and adaeted to the ~eeroduction ox hass Lange si~Jnals supplied by the headphone amplifier and tLansmitted by means of suitable wiring. which ~UIIS between two layers of the sueportive band.
Said contact tcansducers 16, or body transducers, sueply tactile bass sensations to the listener's body. The bass signals may be filtered by a low-pass filter circuit at the amelifier output, and they may be suplied by the left and right program channel to transduces located on the leEt and tight poction of the band 6, respectively, or they may provide from a single channel resulting from the addition of the left and right signal. additional contact transducers may be positioned at the concave faces of two shoulder straps, provided with signal conductors, and connected at both ends to the supportive and interconnective band 6.
The headphone amplifier may be replace by an integcated tuner-amplifier and decoder adapted for the reception and decodification of F~ stereo signals, and for the reception of other wave bands, including AM, television audio signals, cordless microphones, and receiverJ~ransmi~ter bands.
The tuner circuitry may include automatic program searching, automatic frequency control automatic stereo/mono blending, noise reduction, frequancy synthesizing, electronic ~ead-outs etc. The tuner, or radio receiver, may also consist of a separate unit, which may replace the elayback unit 1, or be added to the devices 1 or 2 or positioned elsewhere, preferably by snap-in coupling means, providing for electrical connection to the system.
n FM ceception antenna is connected ~.o the cletector input of the radio receiver. The reception antenna may also run inside a separate strip which may be variously eositioned, for instance as a shoulder strie fixed onto the waist band 6 by its two ends and running vertically or diagonally on the user's upper trunk.
In its preferred and most effective embodiment the system for high fidelity steceophonic reproduction includes a pair of high quality miniatuce microphones 7, positioned on the left and right sides of the supppoctive band 6 (front portion, outer face) or on the left and right casings of the devices 1 and 2, or adjacent to the headphones Ol on the left and right side of the headphones' headband; two corresponding microphone amplifiers, positioned inside the same casing of headphone amplifiers 2, or adjacent to the microphone capsules 7: and a mixing circuit of two-plus-two channels integrated to the ereampli~ying section of the headphone amplifiers 2: which microphones microphone amplifiers, and mixing circuitry are adapted to pick up environmental sounds, stereophonically, and allow for their reproduction simultaneously with the program source, in variable proportion, according to the position of a corresponding control, located on the casing of the headphone amplifiers 2.
The interference of environmental noise, as perceived -through open-air headphones, may be offset, if wanted, through acoustic cance].lation techniques applied to the same noise signals as captured through the microphones.
The preamplifying stage of the headphone ampli.fiecs 2 may be adapted for and provided with a variety oE modifying cirucits to obtain, for example, the separate control o different portions oE the frequency spectrum, the control the of the dynamic range of the program signal, noise reduction, and other effects. Automatic loudness compensation may be included to provide for bass and treble compensation at low listening levels, accocding to the reproduction or as recorded ir. the ear channels or an essentially exact limitation of a listener's head (dummy head), will be accurately reproduced at the ears of the user, or of other listeners, in such a way that the spatial imaging of the reproduced sound sensations is highly accurate, concerning any of its parameters (depth, horizontal separation, vertical location, front/back distribution), with regard to the sound sensations obtained by a listener located at the original recording setting in the position of the probe microphone set-up.
(Gebrau~hsmuster 7,509,223 Federal Republic of Germany).
The present invention may still include other arrangement to offset a well known shortcoming of headphone reproduction, which comprises a small size counter-weight sensor of head movements situated at the top of the headband support of the headphones 3 approximately on the axis of the - ~6 -6~1 listeneL's horizontal head movements) and connected to phase and fLequency control circuitry located inside the casing of the amplifiers 2 or in a separate casing to be plugged therei.n which means are adpated to simulate a change in the direction of the reproduced sound sensations in such a way that sudden rotational movement ox the listener or of the listener's head, on a hocizontal plane, are not accompanied by corresponding shifts of the reproduced sound sensations, which seems to remain in their original direction and to occupy a stable 10 position in the listener's environment (U.S. Patent 3,962,5~3).
Other devices may be attached to the system as separate elug-in modules, ox they may be included in multifunctional embodiments of the two main units l and 2.
Such additional functions may include an electLonic sound synthesizer and/or an electronic rhythm generator, the output signal of which may be routed to the mixing circuit instead of onle or two microphone channels or of the recorded or broadcast program source.
A biofeedback system may be similarly connected to the system, being adpated to pick up brainwave, skin ressitance, or heaLt beat signals, from the user's body, through appropriate pick-up means suitably locatsd and connected to a CiLCUit converting them to the audio range and supplying them to the headphone amplifiers 2, either via the mixing circuit or not, for reproduction through the headphones 3. Said biofeedback system allows for the progressive control of some of the listeners physioloqical variables through auditory ~onitocing.
The system also may include the necessary cicuitcy to allow for transmitter/receiver communication of any waveband or kind, including the citizen band type or voice communication, wherein the circuits are comprised in a separate unit, to be plugged into the headphone amplifiers 2 or the receiver may be integrated to the broadcast radio receiver and the transmitter to the cordless headphone transmitters mentioned above. The corresponding antenna may be attached to or built into a separte shoulder strap; it it is positioned adjacent to any wiring lO, which may represent a source of interference and noise, said wiring may be shielded by a protective conduit.
The present reproduction system may at the same time be a stereophonic recording system, if the playback device l is equipped with recording and erasing heads and includes recording circuitry adapted for stereophonic recording of audio signals supplied by the broadcast program source, the microphones 7, or by an auxiliary input.
The microphones also may be of the cordless type, in which case they are provided with a power source, a transmitter circuit, and a transmitting antenna, the corresponding receiver, or two receivers (left and right channel) may be integrated to the broadcast receiver, or constitute a separate unit, located in any of the casings l (together with the playback device) or 2 (together with the mixing circuit), or plugged into these casings with the corresponding antenna ~L~3~6~3 running alonq band 6, ox on a separate strip. Otherwise, the microehones 7, either included for direct Le~roduc~ion, or for sound recording, or foc hoth, may be positioned directly on the supportive band 6, as shown in the drawings, and they may also be detachable, and connected to the microphone ampliiers and the recording and/or mixing circuitry by wire means, or they may be eositioned adjacently to the headphones.
The auxiliary input, which may also be connected to the mixing circuit, may also be adopted to accept, among other audio signals, the signals generated by electric music instruments, like a batteLy-operated electronic synthesizer.
The system, equipped for stereophonic recording, may be further adaeted for the synchronization of live sound recordings with the cinematograehic or elec-tronic recording of corresponding live images by separate means, thus including a synchronizing pulse input and output, or a crystal synchronizing pulse generator, and motor speed control means, all situa-ted at the elayback device l, and allowing Eor pulse-by-pulse speed matching between sound and image recording.
In the resent invention the parts and circuits are combined into a unique and highly original a~angement, both physically and electronically. Any embodiment will include the basic elements of battery operated binaural high fidelity reproduction, plus a given choice of supplementary equipment.
Such supplementary equipment will either enlarge the number of signal sources or the audio processing capabilities of the .
~.~.3~
basic system. Obviously, an unlimited number of miniaturi7.ed and battery opeLated circuits may be used at any stage, iE said ciruits aLe formed as plug-in modules to be included alternatively, rather than simultaneously, in the present system fox high fidelity reeroduction.
The circuits and devices included in the present system are preferably arranged as a modular system, each module consituting a separate until including one or serveral functions, being provided with snap-in coupling means that allow for fastening in such a way that mechanical fixation is achieved together with electrical connection to the signal path and power supply. Said modules provide for flexibilty for use in that they may be easily detached a reattached, possibly in a variety of placements allowing for optimal comfort in different positions of the listener, or for check-out and repair operations, or for replacement of one junction by another.
The modular system may also include a second supporting band 6, identical in structure to the first band, provided with a second set of rechargeable batteries and battery casings, so that the listener may connect one band provided with rechargeable batteries to a recharged transformer connected to a mains-power source in order to recharge said batteries, while using the other band 6 with the other set of batteries.
The circuits and devices of the present reproduction system, or part thereof, either adapted as plug-in modules or 3L~3q)q~
not, may be miniatuLized to the utmost and fully integrated to a suppoLting band, so as Jo form a compact unity with said band, resulting in a single strip without protruding bodies, of sufficient width and thickness to comprehend said circuits and devices formed as plate members and distributed along the band between different layers thereof, while showing the controls and read-outs on its convex face.
Although only one embodiment of the invention has been illustrated in the drawings, various changes in the form and relative arrangement of the parts will now appear obvious to one skilled in the art and may be made without departing from the spirit and scope of the present invention as defined in the appended claims. Similarly, different memory devices may be used, and changes may be made in other aspects of high fidelity technique, without departing from the basic concept of the present invention.
COM~æRCIAL APPLICATIONS
The pLoposed system offers wide applicability from a combination of high fidelity, low cost and modular Elexibility with the elmination of all space restrictions to the reproduction. The wideseread contemporary use ox high fidelity sterPophonic installations and particularly the recent trend toward automobile high fidelity indicate an important need for a system of this kind.
~3~
Owing to the particu1aL effect of high ~luality music reproduction in association with lis~ener's motion states, an important apelication of the described arrangement lies in reproduction during seort or transportative activities such as skiing, motorcycle Liding, car driving.
Ample versatility including domestic and automobile applications make it into an important alternative for existing high fidelity reproduction system. Realistic sound reproduction and the absence of physical encumbrance and social distrubance also make it into a superior alternative for today's battery-operated stereophonic portables.
The system displays an original and highly effective function ducing promenades and in the open environment of natural landscapes like a beach, a park, or the mountains. It is equally useful and entertaining for travelling and in holiday situations.
fulfillment of important needs is also seen in the peculiar fact that the pLesent system can be as effective for prlvate entertainment and isolation from ongoing activities as for socializing and for the shared stipulation given by lifelike reproduction of music and by the stereophonic amplification of real-life sounds and sound enviLonments.
The system can also be used in the hours often lost in public transportation, and its applications include self-instructional activities as msuch as the recording of messages or spoken correspondence - including real-life 3~
back~ound sounds - in steLeo. As a ready--to--use recording and monitoring system it is apt to establ;sh the practice of life recording (sound hunting). amplified rehearsing (playing, singing) with or without recording, and stereophonic filming for a wide public that presently avoids the emcumbrance of conventional machinery. Buick and inconspicuous mixing, recording and monitoring also make it into an important professional tool - for instance in music, filmmaking, journalism, science. A combination of spoken information with stereophonic music provides further applications in the touristic domain.
Because of its touch-oriented control, and three-dimensional ammplification of surrounding schools, the invention has additional importance for those restricted to sound and touch owing to handicapped eyesight. It may also ye important for people with a weak hearing ability.
Its main and essential functlon lies, however, in the high fidelity stereophonic reæroduction of sound sensations and particularly of music in an unlimited number of environment and situations.
After several decades of high fidelity reproduction, and twenty yeas of an evergrowing stereophonic industry, no arrangement has been produced or proposed for high quality reproduction independently of a fixed location. The solution for portable high fidelity is found in a particular way of using and combining recent tape recorder technology, headphone ~L23~
technology, binaural Leproduction circuitry, integrated circuit techniques, battery operation, and physical arrangement that ties the equipment to the listener's body in a modular fashion.
The resulting system is highly effective, easy to use, and outstandingly flexible. The described apparatus is particularly original in that it does not just offer a new solution for a known function, but, what is moLe, establishes essentially a new function. It is the first system to provide high fidelity reproduction outside of closed environments like home or cars. It is able, in particular, to provide highly accurate pcojection of three-dimensional sound events for a listener who is neither acoustically isolated nor restricted in his own physical space. It thereby intLoduces a new auditory and audiovisual experience, to which corresponds a new potential market.
The proposed system has all the advantages of binaural reproduction and none of its well-known disadvantages. It provides the highest reproduction quality and unpLecedented flexibility at low cost, energy, and encumbrance, and it opens the way for a variety of innovative uses. For these reasons it is superior, in overall effectiveness, to any devious stereophonic reproduction system.
(12) a s~ring/mass suseension system having damping characteristics that isolate the eerformance of the high fidelity devices from the interference of mechanical vibrations.
The system is able to eroject three-dimensional acoustic environments and sound events in high definition for a listener who is himself unrestricted in his mobility and choice of physical environments, thereby creating a new and unique acoustic and audiovisual experience.
BRIEF DESCRIPTION OF THE DRAWINGS
The functional and constructive characteristics of the present invention will become more apparent from the following description, in which reference is jade to the acçompanying drawings, which illustrate an exemplificative and not limitative embodiment of the invention for high fidelity stereophonic reproduction, and wherein -Fig. 1 is a front view of a system, equipped with devices for high fidelity stereophonic reproduction:
Fig. 2 is a back view of the same system:
Fig. 3 is a view of a supporting and interconnective Rand without any of the casings and respective devices:
Fig. 4 illustrates an example of application of the present invention.
The system for high fidelity stereophonic reproduction ~3~6~
includes four main paLts:
(i) a playback device 1, (ii) a pair of high fidelity headphone amplifiers, (iii) a pair of high fidelity headphones (or earphones) 3, tiv) one or more battery casings 4 (containing batteries 5).
In the referred embodiment other parts are equally important:
a pair of miniature microphones 7, a eair of microphone amplifiers, four-channel mixing circuitry, a high fidelity broadcast FM receiver, an FM stereo decoder The following accessory elements complete the basic arrangement:
a band and a buckle 8, an extensible eortion 9, inte~connective wiring -Eor signal and power transmission lO, an antenna 11.
The invention may further comprise:
a number oE padding cushions 12, a support structure or casing 13 for magnetic tape cassettes 14, -- ZO --~3~
another structure 15 to SUppoLt the headphones 3 in collapsed foLm, a elurality of contact tcansduce~s 16, spring/mass damping mechanics for the suspension of the playback device and various circuits.
Naturally, it is understood that the instant system be so designed that all its circuits and devices are miniaturized to the utmost and may be built into the band 6 in a compact and integrative way, and that they may be contained in any number of housings, variously distributed alongside the band.
Referring now to its constituent parts in more detail, the system for high fidelity stereophonic reproduction compzises a high Eidelity playback device 1 effective to pick up stereoehonic audio signals from magnetic tape cassettes 14 OL other carrier of recorded audio information memory devices), and supply them to an output end, which connects to a pair of high fidelity headphone amplifiers 2 by means of wire connections lO. arranged betwean two layers of the supporting band 6.
The fixation of the devices 1, 2 and other circuitry, in their respective casings may be obtained with the inclusion of spring~mass damping systems located between the casings and the devices contained therein, or between the coupling pats of all other parts of the devices 1 and 2, or integrated to the li, ~30~6~
coupling warts located on the band 6, wherein said dameing systems have low-pass characteristics that adequately isola-te the reproduction devices from shocks and vibrations, above a predetermined frequency, originating from the user's bodily movements.
The playback device 1, the headphone amplifieLs 2 and all other circuitry that may optionally be included and is referred Jo below, are adapted for battery operation. The hatteries 5, preferably of rechargeable type, are provided in sufficient numbec and size foc the operation of the various devices of the system durinq a useful length of time, and are located inside of one or more appropriate casings 4, equipeed with contact ends and supplying vower to the devices through wiring 10, running along or inside the band 6. alternatively, said batteries may be directly housed inside the casings of the devices 1 and 2.
n ac/dc voltage converter may also be included to increase the voltage of the power supply, if the circuitry of the system is designed to operate at relatively higher voltage while using only a small number of batteries.
The playback device 1 may include its own preamplifying stave, adapted to the characteristics of the eick-u~ head and to one or several types of signal carrier (memory device), like a cassette type a miniature disc, or a hologram, which are to be introduced into the elayback device 1, preferably by means of a slot-load mechanism. The partially - ~2 -, .
., .
~351~6~
amplified ste~eoLhonic signal is delivered, through appLo~riate output ends, to the wiving lO, which supplies the same signal to the input ends of the headphone amplifiecs 2. The elayback device 1 may be provided with all capabilities of recent reeroduction technology, like automatic program seacching, noise reduction circuitry, digital read-outs, etc.
The headehone amplifiers 2 may include a preamplifying stage comprising volume, balance, tone control and switching weans, together with a main amplifying stage. The amplifier is provided with one or preferably several headphone outputs, to which one OL more pairs of headphones 3 can be connected.
The headphones 3 of the lightweight and high fidelity characteristics, are preferably of the "open air" nonisolating type and may include a headband sup~oLt OL be directly fixed to the ears. The headband support is preferably formed with a foLdable or collapsible structure.
A short range, high quality stereophGnic transmitter, either contained in the same casing of the headphone amplifieLs 2, or in a separate casing, may be connected to the preamplifier output to provide for the cordless connection of an unlimited number of headphone pairs 3, each provided with its own pair of receivers and reception antennas, stereoehonic amplifier, and power supply. The stereophonic transmitter is also connected to an antenna for signal transmission.
The system for high fidelity stereophonic reproduction may also include a elurality ox contact transducers 16 ~3~
dist~ihuted alon-Jside the innec face of the suppoLtin-~ band 6, and adaeted to the ~eeroduction ox hass Lange si~Jnals supplied by the headphone amplifier and tLansmitted by means of suitable wiring. which ~UIIS between two layers of the sueportive band.
Said contact tcansducers 16, or body transducers, sueply tactile bass sensations to the listener's body. The bass signals may be filtered by a low-pass filter circuit at the amelifier output, and they may be suplied by the left and right program channel to transduces located on the leEt and tight poction of the band 6, respectively, or they may provide from a single channel resulting from the addition of the left and right signal. additional contact transducers may be positioned at the concave faces of two shoulder straps, provided with signal conductors, and connected at both ends to the supportive and interconnective band 6.
The headphone amplifier may be replace by an integcated tuner-amplifier and decoder adapted for the reception and decodification of F~ stereo signals, and for the reception of other wave bands, including AM, television audio signals, cordless microphones, and receiverJ~ransmi~ter bands.
The tuner circuitry may include automatic program searching, automatic frequency control automatic stereo/mono blending, noise reduction, frequancy synthesizing, electronic ~ead-outs etc. The tuner, or radio receiver, may also consist of a separate unit, which may replace the elayback unit 1, or be added to the devices 1 or 2 or positioned elsewhere, preferably by snap-in coupling means, providing for electrical connection to the system.
n FM ceception antenna is connected ~.o the cletector input of the radio receiver. The reception antenna may also run inside a separate strip which may be variously eositioned, for instance as a shoulder strie fixed onto the waist band 6 by its two ends and running vertically or diagonally on the user's upper trunk.
In its preferred and most effective embodiment the system for high fidelity steceophonic reproduction includes a pair of high quality miniatuce microphones 7, positioned on the left and right sides of the supppoctive band 6 (front portion, outer face) or on the left and right casings of the devices 1 and 2, or adjacent to the headphones Ol on the left and right side of the headphones' headband; two corresponding microphone amplifiers, positioned inside the same casing of headphone amplifiers 2, or adjacent to the microphone capsules 7: and a mixing circuit of two-plus-two channels integrated to the ereampli~ying section of the headphone amplifiers 2: which microphones microphone amplifiers, and mixing circuitry are adapted to pick up environmental sounds, stereophonically, and allow for their reproduction simultaneously with the program source, in variable proportion, according to the position of a corresponding control, located on the casing of the headphone amplifiers 2.
The interference of environmental noise, as perceived -through open-air headphones, may be offset, if wanted, through acoustic cance].lation techniques applied to the same noise signals as captured through the microphones.
The preamplifying stage of the headphone ampli.fiecs 2 may be adapted for and provided with a variety oE modifying cirucits to obtain, for example, the separate control o different portions oE the frequency spectrum, the control the of the dynamic range of the program signal, noise reduction, and other effects. Automatic loudness compensation may be included to provide for bass and treble compensation at low listening levels, accocding to the reproduction or as recorded ir. the ear channels or an essentially exact limitation of a listener's head (dummy head), will be accurately reproduced at the ears of the user, or of other listeners, in such a way that the spatial imaging of the reproduced sound sensations is highly accurate, concerning any of its parameters (depth, horizontal separation, vertical location, front/back distribution), with regard to the sound sensations obtained by a listener located at the original recording setting in the position of the probe microphone set-up.
(Gebrau~hsmuster 7,509,223 Federal Republic of Germany).
The present invention may still include other arrangement to offset a well known shortcoming of headphone reproduction, which comprises a small size counter-weight sensor of head movements situated at the top of the headband support of the headphones 3 approximately on the axis of the - ~6 -6~1 listeneL's horizontal head movements) and connected to phase and fLequency control circuitry located inside the casing of the amplifiers 2 or in a separate casing to be plugged therei.n which means are adpated to simulate a change in the direction of the reproduced sound sensations in such a way that sudden rotational movement ox the listener or of the listener's head, on a hocizontal plane, are not accompanied by corresponding shifts of the reproduced sound sensations, which seems to remain in their original direction and to occupy a stable 10 position in the listener's environment (U.S. Patent 3,962,5~3).
Other devices may be attached to the system as separate elug-in modules, ox they may be included in multifunctional embodiments of the two main units l and 2.
Such additional functions may include an electLonic sound synthesizer and/or an electronic rhythm generator, the output signal of which may be routed to the mixing circuit instead of onle or two microphone channels or of the recorded or broadcast program source.
A biofeedback system may be similarly connected to the system, being adpated to pick up brainwave, skin ressitance, or heaLt beat signals, from the user's body, through appropriate pick-up means suitably locatsd and connected to a CiLCUit converting them to the audio range and supplying them to the headphone amplifiers 2, either via the mixing circuit or not, for reproduction through the headphones 3. Said biofeedback system allows for the progressive control of some of the listeners physioloqical variables through auditory ~onitocing.
The system also may include the necessary cicuitcy to allow for transmitter/receiver communication of any waveband or kind, including the citizen band type or voice communication, wherein the circuits are comprised in a separate unit, to be plugged into the headphone amplifiers 2 or the receiver may be integrated to the broadcast radio receiver and the transmitter to the cordless headphone transmitters mentioned above. The corresponding antenna may be attached to or built into a separte shoulder strap; it it is positioned adjacent to any wiring lO, which may represent a source of interference and noise, said wiring may be shielded by a protective conduit.
The present reproduction system may at the same time be a stereophonic recording system, if the playback device l is equipped with recording and erasing heads and includes recording circuitry adapted for stereophonic recording of audio signals supplied by the broadcast program source, the microphones 7, or by an auxiliary input.
The microphones also may be of the cordless type, in which case they are provided with a power source, a transmitter circuit, and a transmitting antenna, the corresponding receiver, or two receivers (left and right channel) may be integrated to the broadcast receiver, or constitute a separate unit, located in any of the casings l (together with the playback device) or 2 (together with the mixing circuit), or plugged into these casings with the corresponding antenna ~L~3~6~3 running alonq band 6, ox on a separate strip. Otherwise, the microehones 7, either included for direct Le~roduc~ion, or for sound recording, or foc hoth, may be positioned directly on the supportive band 6, as shown in the drawings, and they may also be detachable, and connected to the microphone ampliiers and the recording and/or mixing circuitry by wire means, or they may be eositioned adjacently to the headphones.
The auxiliary input, which may also be connected to the mixing circuit, may also be adopted to accept, among other audio signals, the signals generated by electric music instruments, like a batteLy-operated electronic synthesizer.
The system, equipped for stereophonic recording, may be further adaeted for the synchronization of live sound recordings with the cinematograehic or elec-tronic recording of corresponding live images by separate means, thus including a synchronizing pulse input and output, or a crystal synchronizing pulse generator, and motor speed control means, all situa-ted at the elayback device l, and allowing Eor pulse-by-pulse speed matching between sound and image recording.
In the resent invention the parts and circuits are combined into a unique and highly original a~angement, both physically and electronically. Any embodiment will include the basic elements of battery operated binaural high fidelity reproduction, plus a given choice of supplementary equipment.
Such supplementary equipment will either enlarge the number of signal sources or the audio processing capabilities of the .
~.~.3~
basic system. Obviously, an unlimited number of miniaturi7.ed and battery opeLated circuits may be used at any stage, iE said ciruits aLe formed as plug-in modules to be included alternatively, rather than simultaneously, in the present system fox high fidelity reeroduction.
The circuits and devices included in the present system are preferably arranged as a modular system, each module consituting a separate until including one or serveral functions, being provided with snap-in coupling means that allow for fastening in such a way that mechanical fixation is achieved together with electrical connection to the signal path and power supply. Said modules provide for flexibilty for use in that they may be easily detached a reattached, possibly in a variety of placements allowing for optimal comfort in different positions of the listener, or for check-out and repair operations, or for replacement of one junction by another.
The modular system may also include a second supporting band 6, identical in structure to the first band, provided with a second set of rechargeable batteries and battery casings, so that the listener may connect one band provided with rechargeable batteries to a recharged transformer connected to a mains-power source in order to recharge said batteries, while using the other band 6 with the other set of batteries.
The circuits and devices of the present reproduction system, or part thereof, either adapted as plug-in modules or 3L~3q)q~
not, may be miniatuLized to the utmost and fully integrated to a suppoLting band, so as Jo form a compact unity with said band, resulting in a single strip without protruding bodies, of sufficient width and thickness to comprehend said circuits and devices formed as plate members and distributed along the band between different layers thereof, while showing the controls and read-outs on its convex face.
Although only one embodiment of the invention has been illustrated in the drawings, various changes in the form and relative arrangement of the parts will now appear obvious to one skilled in the art and may be made without departing from the spirit and scope of the present invention as defined in the appended claims. Similarly, different memory devices may be used, and changes may be made in other aspects of high fidelity technique, without departing from the basic concept of the present invention.
COM~æRCIAL APPLICATIONS
The pLoposed system offers wide applicability from a combination of high fidelity, low cost and modular Elexibility with the elmination of all space restrictions to the reproduction. The wideseread contemporary use ox high fidelity sterPophonic installations and particularly the recent trend toward automobile high fidelity indicate an important need for a system of this kind.
~3~
Owing to the particu1aL effect of high ~luality music reproduction in association with lis~ener's motion states, an important apelication of the described arrangement lies in reproduction during seort or transportative activities such as skiing, motorcycle Liding, car driving.
Ample versatility including domestic and automobile applications make it into an important alternative for existing high fidelity reproduction system. Realistic sound reproduction and the absence of physical encumbrance and social distrubance also make it into a superior alternative for today's battery-operated stereophonic portables.
The system displays an original and highly effective function ducing promenades and in the open environment of natural landscapes like a beach, a park, or the mountains. It is equally useful and entertaining for travelling and in holiday situations.
fulfillment of important needs is also seen in the peculiar fact that the pLesent system can be as effective for prlvate entertainment and isolation from ongoing activities as for socializing and for the shared stipulation given by lifelike reproduction of music and by the stereophonic amplification of real-life sounds and sound enviLonments.
The system can also be used in the hours often lost in public transportation, and its applications include self-instructional activities as msuch as the recording of messages or spoken correspondence - including real-life 3~
back~ound sounds - in steLeo. As a ready--to--use recording and monitoring system it is apt to establ;sh the practice of life recording (sound hunting). amplified rehearsing (playing, singing) with or without recording, and stereophonic filming for a wide public that presently avoids the emcumbrance of conventional machinery. Buick and inconspicuous mixing, recording and monitoring also make it into an important professional tool - for instance in music, filmmaking, journalism, science. A combination of spoken information with stereophonic music provides further applications in the touristic domain.
Because of its touch-oriented control, and three-dimensional ammplification of surrounding schools, the invention has additional importance for those restricted to sound and touch owing to handicapped eyesight. It may also ye important for people with a weak hearing ability.
Its main and essential functlon lies, however, in the high fidelity stereophonic reæroduction of sound sensations and particularly of music in an unlimited number of environment and situations.
After several decades of high fidelity reproduction, and twenty yeas of an evergrowing stereophonic industry, no arrangement has been produced or proposed for high quality reproduction independently of a fixed location. The solution for portable high fidelity is found in a particular way of using and combining recent tape recorder technology, headphone ~L23~
technology, binaural Leproduction circuitry, integrated circuit techniques, battery operation, and physical arrangement that ties the equipment to the listener's body in a modular fashion.
The resulting system is highly effective, easy to use, and outstandingly flexible. The described apparatus is particularly original in that it does not just offer a new solution for a known function, but, what is moLe, establishes essentially a new function. It is the first system to provide high fidelity reproduction outside of closed environments like home or cars. It is able, in particular, to provide highly accurate pcojection of three-dimensional sound events for a listener who is neither acoustically isolated nor restricted in his own physical space. It thereby intLoduces a new auditory and audiovisual experience, to which corresponds a new potential market.
The proposed system has all the advantages of binaural reproduction and none of its well-known disadvantages. It provides the highest reproduction quality and unpLecedented flexibility at low cost, energy, and encumbrance, and it opens the way for a variety of innovative uses. For these reasons it is superior, in overall effectiveness, to any devious stereophonic reproduction system.
Claims (10)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A personal stereo sound system, to be carried and used on the person of at least one individual listener, comprising the combination of:
(i) a miniaturized program source device arranged to produce simultaneous mutually different stereo program output signals;
(ii) minuaturized stereo signal amplifier means, impedance matched to, and arranged to receive said stereo output signals from said source device;
(iii) miniaturized lightweight paired stereo headphone means, physically remote from said source device, impedance and sensitivity matched to and arranged to receive separately, one signal for each phone, the output signals of said amplifier means through separate cable means;
(iv) volume adjusting means for the signals received by said headphone means; and (v) power source means comprising a battery electrically connected to said amplifier means and to said source device and housed together with said amplifier means and source device in a single portable unit no larger than hand size.
(i) a miniaturized program source device arranged to produce simultaneous mutually different stereo program output signals;
(ii) minuaturized stereo signal amplifier means, impedance matched to, and arranged to receive said stereo output signals from said source device;
(iii) miniaturized lightweight paired stereo headphone means, physically remote from said source device, impedance and sensitivity matched to and arranged to receive separately, one signal for each phone, the output signals of said amplifier means through separate cable means;
(iv) volume adjusting means for the signals received by said headphone means; and (v) power source means comprising a battery electrically connected to said amplifier means and to said source device and housed together with said amplifier means and source device in a single portable unit no larger than hand size.
2. A personal stereo listening system, as claimed in Claim 1 comprising equalizer means compensating signal distortions produced by said headphone means.
3. A personal stereo listening system, as claimed in Claim 1, comprising stereo radio receiver means connected to supply stereo output signals to said amplifier means, said radio receiver means and said amplifier means being electrically connected to said power source means.
4. A system according to Claim 1 including a noise reduction means included in said program source.
5. A personal listening system, as claimed in Claim 1, wherein said program source device is a playback apparatus for the reproduction of stored program signals.
6. A listening system, as claimed in Claim 1, wherein the stereo program source device includes means for playing a magnetic tape cassette.
7. A personal listening system, as claimed in Claim 1, wherein said source device includes a playback apparatus, a motor drive for said playback apparatus, a stereo pick-up head, and stereo pre-amplifiers connected to receive output signals from said pick-up head.
8. A system according to Claim 1 in which said headphones are collapsible.
9. A listening system as claimed in Claim 1, wherein said system includes stereo signal equalizers, electrically connected to respective output channels of said stereo signal amplifier means, and a reproduction playback device as a program source device.
10. A system of apparatus according to Claim 1, in which the signal amplifiers are fed stereo signals from stereo pre-amplifiers which amplify stereo signals from a magnetic tape cassette playback device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000438884A CA1230060A (en) | 1979-06-12 | 1983-10-12 | High fidelity stereophonic reproduction system |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US4796779A | 1979-06-12 | 1979-06-12 | |
| US047,967 | 1979-06-12 | ||
| CA000336116A CA1157382A (en) | 1979-06-12 | 1979-09-21 | High fidelity stereophonic reproduction system |
| CA000438884A CA1230060A (en) | 1979-06-12 | 1983-10-12 | High fidelity stereophonic reproduction system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1230060A true CA1230060A (en) | 1987-12-08 |
Family
ID=25668967
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000438884A Expired CA1230060A (en) | 1979-06-12 | 1983-10-12 | High fidelity stereophonic reproduction system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1230060A (en) |
-
1983
- 1983-10-12 CA CA000438884A patent/CA1230060A/en not_active Expired
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| MKEX | Expiry |