US3398810A - Locally audible sound system - Google Patents
Locally audible sound system Download PDFInfo
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- US3398810A US3398810A US640893A US64089367A US3398810A US 3398810 A US3398810 A US 3398810A US 640893 A US640893 A US 640893A US 64089367 A US64089367 A US 64089367A US 3398810 A US3398810 A US 3398810A
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- 230000005236 sound signal Effects 0.000 description 22
- 238000010586 diagram Methods 0.000 description 13
- 230000000284 resting effect Effects 0.000 description 13
- 230000010363 phase shift Effects 0.000 description 12
- 239000003990 capacitor Substances 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- 229910052754 neon Inorganic materials 0.000 description 3
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 description 3
- 239000000969 carrier Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 238000002955 isolation Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/18—Methods or devices for transmitting, conducting or directing sound
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R27/00—Public address systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2217/00—Details of magnetostrictive, piezoelectric, or electrostrictive transducers covered by H04R15/00 or H04R17/00 but not provided for in any of their subgroups
- H04R2217/03—Parametric transducers where sound is generated or captured by the acoustic demodulation of amplitude modulated ultrasonic waves
Definitions
- Two constant-amplitude beams of ultrasonic sound are directed to intersect at a region where sound intelligence is to be heard.
- One of the beams i.e., a carrier
- Prior tica- Sprague 1,616,639 discloses a high frequency sound system wherein two loud speakers are placed at opposite ends of an auditorium. An ultrasonic signal is fed to both speakers. The ultrasonic signal fed to one speaker is amplitude modulated by an audio signal to produce two side bands, one of which is filtered out. In the area of intersection of the waves output by the two speakers, the amplitude of audio sound is determined by the amplitude of the modulated wave. The speaker reproducing the modulated wave has no output between periods of modulation, and during modulation, the wave front produced thereby is audible as noise.
- the object of this invention is to provide a sound system particularly adapted for displays at museums, art galleries and the like wherein no audible sound is reproduced except, for example, directly in front of a display.
- a spectator in front of one display will not hear cross-talk from an explanatory lecture relating to another display.
- it is intended to provide two intersecting beams of sound, neither of which produces audible intelligence or even audible noise when heard alone, but which do produce audible intelligence when combined in a comparatively small area of intersection.
- selected portions of an audience can be singled out to receive audible intelligence while all others in the audience, even those in the beam paths, will hear nothing.
- the area of intersection and, hence, spread of audio intelligence can be varied by similarly varying the resting frequency of the carrier and the other beam.
- the same end can be accomplished by the use of acoustic lenses or by varying the physical construction of the transducers.
- the area of intersection may also be altered by varying the angle of incidence of the intersecting 3,398,810 Patented Aug. 27, 1968 beams. By such means, a readily definable area of audible intelligence may be created.
- a frequency-controlled supersonic whistle or like device may be used for dooding an area with unmodulated supersonic sound at the carriers resting frequency; whereupon a beamed phase modulated acoustical signal from a directional transducer will produce a line of audible intelligence through the area.
- a parabola which produces a cone-shape acoustical signal which may be used in connection with a non-directional transducer for the unmodulated acoustical signal, or in connection with a directional transducer for the same.
- the system may also have military applications for beaming instruction from an aircraft or a command post to a selected group of troops.
- FIG. l is a series of waveform diagrams illustrating the operation of the invention in comparison with the known prior art
- FIG. 2 is an elemental waveform diagram illustrating phase shift
- FIG. 3 is an elemental circuit diagram illustrating operation of a phase-shifting circuit
- FIG. 4 is a simplified circuit diagram illustrating one type of phase-shifting circuit
- FIG. 5 is a simplified circuit diagram illustrating another type of phase-shifting circuit
- FIG. 6 is a block diagram of one embodiment of the subject system
- FIG. 7 is a block diagram of the system of FIG. 6 showing some details of the components.
- FIGS. 8 and 8A are diagrams illustrating the effects of transducer signal spread on the areas of intersection of their acoustical signals.
- an audio signal S is used to amplitude-modulate a 30 kc. carrier C, 4thus producing two sidebands which are illustrated as C-l-S and C-S, both of which vary in amplitude according to the amplitude of the audio signal.
- C-l-S and C-S both of which vary in amplitude according to the amplitude of the audio signal.
- Sprague saliva
- one or the other of the sidebands is ltered out, leaving an output which varies in amplitude A as diagrammed at the lower left-hand portion of FIG. l.
- Etiher C-l-S or C-S is beat against another superaudible signal like the 30 kc. carrier, and the resultant is intended to produce audible intelligence at the area of intersection.
- FIG. l diagrammatically illustrates the invention.
- an audio signal S is used to modulate 30 kc. carrier.
- the carrier is phase modulated so as to produce a signal fm which is of constant amplitude A', but which varies in instantaneous phase according to the frequency of the modulating audio signal. Only the audio frequency is filtered out.
- the modulating audio signal produces phase-shift in the carrier which then contains two sidebands of variable frequency, both of which vare propogated; the rate of phase shift is determined by the instantaneous rate of the audio frequency and the degree or angle of the phase shift is accomplished by the amplitude of the audio signal.
- the basic requirements are that one acoustical signal of constant amplitude and frequency be beamed towards an area of intersection, and that there also be beamed towards the area of intersection ⁇ another acoustical signal, or carrier, which is phase-shifted by the audio signal to be heard, in the manner elementarily illustrated in FIG. 1.
- the wave form diagram illustrates the characteristics of a phase-shifted carrier wave resulting frojm modulation by audio frequency signals, the full line waveform representing modulation by an audio frequency signal of one amplitude and the dash line waveform representing modulation yby an audio frequency signal of another amplitude.
- FIG. 4 illustrates one elemental type of phase-shifting device which is usuable in the subject system.
- a 30 kc. signal from an oscillator is input at IN across the series combination of capacitor c and photoresistor pr.
- This signal is be phase-shifted in accordance with the output of an audio amplifier labeled audio.
- a neon tube N is connected by the output of the audio amplifier, with a diode d in one side of the tube circuit.
- Exposed to the illumination of the neon tube is a photoresistor pr whose resistance varies according to the illumination of the neon tube.
- photoresistor serves the function of resistor r in FIG. 3.
- the phase of the output signal will be shifted according to the frequency and -amplitude of the output of the audio amplifier. Suitable bias may be inserted for the nenon tube for predetermining the level of audio signal needed to fire it, or to assume linear operation.
- FIG. illustrates in elemental diagram a vaccum tube type of phase shifter.
- a carrier signal having, for example, a 30 kc. resting frequency is input to the plate p of vacuum tube VT via capacitor c, and an audio signal is fed in via grid g.
- the phase of the output signal will shift, as in FIG. 2, according to the frequency and amplitude of the audio signal.
- the tube acts like a variable resistor for the carrier signal, whose resistance is varied by the audio signal, like the variable resistors in FIGS. 3 and 4.
- FIG. 4 ⁇ and FIG. 5 the main difference between FIG. 4 ⁇ and FIG. 5 is that the FIG. 4 device fully isolates the output from the audio signal.
- FIG. 6 is a block diagra-m of one one form of the invention
- FIG. 7 illustrates the same form of invention with some of the details filled in.
- audio amplifier 2 which is controlled by a suitable microphone, recorder-reproducer or the like device (not shown).
- the output of an oscillator 4 which produces a supersonic signal, such as at 30 kc., is fed Via an amplifier 6 to one acoustical transducer, i.e, a loudspeaker 8 directed at a point 10.
- the output of oscillator 4 is also fed through an isolation amplifier 12, to a phase-shift modulator 14 which is modulated by the audio signal from audio amplifier 2.
- phase shift modulator 14 is fed via an amplifier 16 and high-pass filter 18 to another acoustical transducer, i.e., loudspeaker 20.
- a tank circuit device 22 is connected between phase-shift modulator 14 and amplifier 18 for trapping out audio frequency signals, the tank circuit serving as an adjunct to high pass filter 18.
- Netiher of the acoustical outputs of loudspeakers 8 or 20 is audible except at the region 10 of intersection.
- the phase-shifted acoustical output signal of speaker 20 is audible except at the region 10 of intersection.
- FIGS. 8 and 8A diagrammatically illustrate the effect of variations in signal spread of the transducers. Obviously, the wider-angle signals from speakers 8', 20' will produce a larger area of intersection 10 than the area of intersection 10 of the acoustical signals from speakers 8, 20.
- FIG. 7 illustrates some details of the block diagram of FIG. 6.
- audio amplifier 2 is connected through a resistor R1 to the grid g of a vacuum tube VT1; and the output of isolation amplifier 12 may also be connected to grid g via a capacitor C1.
- Grid g is coupled to plate p of VT1 via a capacitor C2 which otherwise may comprise the internal capacitance of the tube.
- the plate p of VTI is connected via capacitor C2 to amplifier 16.
- Tank circuit 22, comprising capacitor C3 and inductance L1 in parallel is connected between the plate output circuit of VT1 and B+ for absorbing any audio frequency signals.
- the high-pass filter 18 between amplifier 16 and speaker 4 may comprise a capacitor C4 and inductance L2 connected as shown.
- the phase-shifted acoustical output signal of speaker 20 is of constant desired amplitude and the output signals of both speakers 20 and 8 are above audible frequencies.
- the amplitude of the signal heard by the listener can be adjusted either by changing the amplitude of the audio signal fed to the phase-shifting device, or by varying the amplification of the signals fed to one or the other or both of the transducers, or by varying the phase-shifting capability of the phase-shifting device.
- a whistle or siren tuned to the resting frequency of the modulated signal may be used.
- Another application of the subject system is for paging devices. Let it be assumed that a hospital corridor is flooded by the phase modulated acoustical signal. A doctor may carry on his person a local supersonic oscillator operating at the resting frequency of the modulated signal and a transducer. The interaction of the modulated and immodulated signals, in the region of the doctor, will produce an audible signal which the doctor can hear, but which will be inaudible at any appreciable distance away from the doctor.
- both of said acoustically transmitted signals are transmitted predominantly in respective different directions. 4.
- the step of varying the amplitude of the audible signal by varying the amplitude of one of said acoustically transmitted signals.
- a supersonic acoustical carrer signal of substantially constant arnplitude having a supersonic resting frequency the same as the fixed frequency of the first acoustical signal but which is phase-modulated by an audio frequency signal bearing intelligence to be heard in said portion of said area.
- a system for producing a locally audible sound signal comprising:
- phase of the carrier signal output of the phase-modulating means is maintained at substantially constant amplitude but is shifted in degree in accordance with the amplitude of said audio frequency signal,AV and in rate according to the frequency of said audio frequency signal,
- first and second transducer means may be disposed to project their acoustical outputs in intersecting relationship in a region where locally audible sound is to be reproduced.
- a system for producing locally audible sound comprising,
- oscillator means for producing a supersonic frequency carrier signal of substantially constant amplitude
- first acoustical transducer means connected to said oscillator means for acoustically transmitting said supersonic carrier signal
- phase-shifting means connected to said oscillator means and to the last-named means for phase-shifting said carrier signal in accordance with said audio frequency signal in degree according to the amplitude of said audio frequency signal and in rate corresponding to the frequency of said audio frequency signal and of substantially constant amplitude
- first and second acoustical transducer means connected to said phase-shifting means for acoustically transmitting said phase-shifted carrier signal, said first and second acoustical transducer means being so disposed with respect to one another that the acoustical outputs thereof intersect one another in an area where locally audible sound is to be heard.
Description
L Aug. 27, 1968 W, T, CLARK l 3,398,810
LOCALLY AUD'IBLE SOUND SYSTEM Filed May 24, 1967 2 Sheets-Sheet l INVENTOR WILLIAM T. CLARK DI Aug- 27, 1968 w. T. CLARK m 3,398,810
LOCALLY AUDIBLE SOUND SYSTEM L Filed May 24, 1967 2 sheets-sheet s LOWER J INSTANTANEOUS f\\\ FREQUENCY l msTAmANEous FREQUENCY s ER sHFT Ne EREo. c 0R-J 1' OUT FIGBA INVENTOR WILLIAM T. CLARK, III
BY H glg I ATTRNEY United States Patent O 3,398,810 LOCALLY AUDIBLE SOUND SYSTEM William T. Clark III, 6 Davis Blvd., New Orleans, La. 70121 Filed May 24, 1967, Ser. No. 640,893 Claims. (Cl. 181-.5)
ABSTRACT OF THE DISCLOSURE Two constant-amplitude beams of ultrasonic sound are directed to intersect at a region where sound intelligence is to be heard. One of the beams, i.e., a carrier, is phase modulated by an audio signal to a produce phaseshift in wave-fronts, the amplitude of the audio modula- -tion being expressed in the degree lof phase shift of the carrier, and the frequency of the audio modulation Ibeing expressed as the rate at which the phase shift takes place. At the region in which the two beams intersect, natural variations in amplitude of the reproduced sound occur because of difference in the phases of the modulated and unmodulated waves; the in-phase components of the modulated and unmodulated beams add, the out of phase components will cancel, and anything between will add or subtract to a greater or lesser degree.
(l) F eId.-The invention is in the class of miscellaneous acoustical systems, supersonic.
(2) Prior arzt- Sprague 1,616,639 discloses a high frequency sound system wherein two loud speakers are placed at opposite ends of an auditorium. An ultrasonic signal is fed to both speakers. The ultrasonic signal fed to one speaker is amplitude modulated by an audio signal to produce two side bands, one of which is filtered out. In the area of intersection of the waves output by the two speakers, the amplitude of audio sound is determined by the amplitude of the modulated wave. The speaker reproducing the modulated wave has no output between periods of modulation, and during modulation, the wave front produced thereby is audible as noise.
The object of this invention is to provide a sound system particularly adapted for displays at museums, art galleries and the like wherein no audible sound is reproduced except, for example, directly in front of a display. Thus, a spectator in front of one display will not hear cross-talk from an explanatory lecture relating to another display. To this end, it is intended to provide two intersecting beams of sound, neither of which produces audible intelligence or even audible noise when heard alone, but which do produce audible intelligence when combined in a comparatively small area of intersection. Also, by directing two such beams at a point of intersection in an auditorium or arena, selected portions of an audience can be singled out to receive audible intelligence while all others in the audience, even those in the beam paths, will hear nothing.
According to this invention, where there are two intersecting beams of ultrasonic sound, one of which, i.e., a carrier, is phase modulated by an audio signal, the area of intersection and, hence, spread of audio intelligence can be varied by similarly varying the resting frequency of the carrier and the other beam. The higher the frequency, the more directional will be the b eams and, hence, the smaller will be the area of intersection. The same end can be accomplished by the use of acoustic lenses or by varying the physical construction of the transducers. The area of intersection may also be altered by varying the angle of incidence of the intersecting 3,398,810 Patented Aug. 27, 1968 beams. By such means, a readily definable area of audible intelligence may be created.
It is also contemplated that instead of beaming the unmodulated acoustical signal, a frequency-controlled supersonic whistle or like device may be used for dooding an area with unmodulated supersonic sound at the carriers resting frequency; whereupon a beamed phase modulated acoustical signal from a directional transducer will produce a line of audible intelligence through the area. Another variation can be obtained using, for one transducer, a parabola which produces a cone-shape acoustical signal which may be used in connection with a non-directional transducer for the unmodulated acoustical signal, or in connection with a directional transducer for the same.
It is believed that the system may also have military applications for beaming instruction from an aircraft or a command post to a selected group of troops.
Furthermore, by placing two directional transducers in spaced opposition to one another, one being energized at the carriers resting frequency and the other energized by the phase-modulated carrier, an area of audible intelligence will be produced vbetween the two transducers.
These and other objects will be apparent from the following specication and drawing, in which:
FIG. l is a series of waveform diagrams illustrating the operation of the invention in comparison with the known prior art;
FIG. 2 is an elemental waveform diagram illustrating phase shift;
FIG. 3 is an elemental circuit diagram illustrating operation of a phase-shifting circuit;
FIG. 4 is a simplified circuit diagram illustrating one type of phase-shifting circuit;
FIG. 5 is a simplified circuit diagram illustrating another type of phase-shifting circuit;
FIG. 6 is a block diagram of one embodiment of the subject system;
FIG. 7 is a block diagram of the system of FIG. 6 showing some details of the components; and
FIGS. 8 and 8A are diagrams illustrating the effects of transducer signal spread on the areas of intersection of their acoustical signals.
Referring first to the left-hand portion of FIG. 1 which, in waveform diagram, represents the prior art, an audio signal S is used to amplitude-modulate a 30 kc. carrier C, 4thus producing two sidebands which are illustrated as C-l-S and C-S, both of which vary in amplitude according to the amplitude of the audio signal. According to Sprague (supra), one or the other of the sidebands is ltered out, leaving an output which varies in amplitude A as diagrammed at the lower left-hand portion of FIG. l. Etiher C-l-S or C-S is beat against another superaudible signal like the 30 kc. carrier, and the resultant is intended to produce audible intelligence at the area of intersection.
The right-hand portion of FIG. l diagrammatically illustrates the invention. As in the prior art, an audio signal S is used to modulate 30 kc. carrier. However, instead of using amplitude modulation, the carrier is phase modulated so as to produce a signal fm which is of constant amplitude A', but which varies in instantaneous phase according to the frequency of the modulating audio signal. Only the audio frequency is filtered out. The modulating audio signal produces phase-shift in the carrier which then contains two sidebands of variable frequency, both of which vare propogated; the rate of phase shift is determined by the instantaneous rate of the audio frequency and the degree or angle of the phase shift is accomplished by the amplitude of the audio signal.
quency-modulating one of the super-sonic signals. The basic requirements are that one acoustical signal of constant amplitude and frequency be beamed towards an area of intersection, and that there also be beamed towards the area of intersection `another acoustical signal, or carrier, which is phase-shifted by the audio signal to be heard, in the manner elementarily illustrated in FIG. 1.
Referring next to FIG. 2, the wave form diagram illustrates the characteristics of a phase-shifted carrier wave resulting frojm modulation by audio frequency signals, the full line waveform representing modulation by an audio frequency signal of one amplitude and the dash line waveform representing modulation yby an audio frequency signal of another amplitude.
FIG. 3 is a diagram illustrating the fundamentals of a phase shifting circuit. Let it be assumed that alternating current from an oscillator is input at IN and passed through either a capacitor c or inductance l in series with a variable resistor r. The phase of the out signal will shift according to the reactance of c or l relative to r at any given frequency. If r=0.l the reactance of c or l, then the phase shift of the output signal approaches 90. If r=lx reactance of c or l, then the phase shift is substantially 0.
FIG. 4 illustrates one elemental type of phase-shifting device which is usuable in the subject system. Let it be assumed that a 30 kc. signal from an oscillator is input at IN across the series combination of capacitor c and photoresistor pr. This signal is be phase-shifted in accordance with the output of an audio amplifier labeled audio. A neon tube N is connected by the output of the audio amplifier, with a diode d in one side of the tube circuit. Exposed to the illumination of the neon tube is a photoresistor pr whose resistance varies according to the illumination of the neon tube. In this instance, photoresistor serves the function of resistor r in FIG. 3. The phase of the output signal will be shifted according to the frequency and -amplitude of the output of the audio amplifier. Suitable bias may be inserted for the nenon tube for predetermining the level of audio signal needed to fire it, or to assume linear operation.
FIG. illustrates in elemental diagram a vaccum tube type of phase shifter. A carrier signal having, for example, a 30 kc. resting frequency is input to the plate p of vacuum tube VT via capacitor c, and an audio signal is fed in via grid g. Here again, the phase of the output signal will shift, as in FIG. 2, according to the frequency and amplitude of the audio signal. The tube acts like a variable resistor for the carrier signal, whose resistance is varied by the audio signal, like the variable resistors in FIGS. 3 and 4. There are many equivalent phase-shifting devices, the main difference between FIG. 4 `and FIG. 5 is that the FIG. 4 device fully isolates the output from the audio signal.
FIG. 6 is a block diagra-m of one one form of the invention, and FIG. 7 illustrates the same form of invention with some of the details filled in. There is audio amplifier 2, which is controlled by a suitable microphone, recorder-reproducer or the like device (not shown). The output of an oscillator 4, which produces a supersonic signal, such as at 30 kc., is fed Via an amplifier 6 to one acoustical transducer, i.e, a loudspeaker 8 directed at a point 10. The output of oscillator 4 is also fed through an isolation amplifier 12, to a phase-shift modulator 14 which is modulated by the audio signal from audio amplifier 2. The output of the phase shift modulator 14 is fed via an amplifier 16 and high-pass filter 18 to another acoustical transducer, i.e., loudspeaker 20. Preferably, a tank circuit device 22 is connected between phase-shift modulator 14 and amplifier 18 for trapping out audio frequency signals, the tank circuit serving as an adjunct to high pass filter 18.
Netiher of the acoustical outputs of loudspeakers 8 or 20 is audible except at the region 10 of intersection. The phase-shifted acoustical output signal of speaker 20,
which varies on one side or the other from a 30 kc. resting frequency, beats against the 30 kc., acoustical output signal of speaker 8 to produce audible intelligence at the region 10 of intersection. Obviously, the extent of region 10 will vary in accordance with the spreads of the acoustical output signals of the speakers, the angle of incidence of the two acoustical signals, and other possible factors mentioned hereinbefore. FIGS. 8 and 8A diagrammatically illustrate the effect of variations in signal spread of the transducers. Obviously, the wider-angle signals from speakers 8', 20' will produce a larger area of intersection 10 than the area of intersection 10 of the acoustical signals from speakers 8, 20.
FIG. 7 illustrates some details of the block diagram of FIG. 6. In this form, audio amplifier 2 is connected through a resistor R1 to the grid g of a vacuum tube VT1; and the output of isolation amplifier 12 may also be connected to grid g via a capacitor C1. Grid g is coupled to plate p of VT1 via a capacitor C2 which otherwise may comprise the internal capacitance of the tube. The plate p of VTI is connected via capacitor C2 to amplifier 16. Tank circuit 22, comprising capacitor C3 and inductance L1 in parallel is connected between the plate output circuit of VT1 and B+ for absorbing any audio frequency signals. The high-pass filter 18 between amplifier 16 and speaker 4 may comprise a capacitor C4 and inductance L2 connected as shown.
In all embodiments, the phase-shifted acoustical output signal of speaker 20 is of constant desired amplitude and the output signals of both speakers 20 and 8 are above audible frequencies. The amplitude of the signal heard by the listener can be adjusted either by changing the amplitude of the audio signal fed to the phase-shifting device, or by varying the amplification of the signals fed to one or the other or both of the transducers, or by varying the phase-shifting capability of the phase-shifting device.
Ordinarily, it would be desirable that all or most of the audio signal be filtered out of the phase-shifted signal produced by transducer 4. However, if desired, a low-level audio signal may be left in the phase-shifted signal for monitoring purposes.
If desired, separate oscillators operating at the same resting frequency, may be used, or instead of producing the unmodulated supersonic signal by an electronic means, a whistle or siren tuned to the resting frequency of the modulated signal may be used.
Another application of the subject system is for paging devices. Let it be assumed that a hospital corridor is flooded by the phase modulated acoustical signal. A doctor may carry on his person a local supersonic oscillator operating at the resting frequency of the modulated signal and a transducer. The interaction of the modulated and immodulated signals, in the region of the doctor, will produce an audible signal which the doctor can hear, but which will be inaudible at any appreciable distance away from the doctor.
The invention is not limited to the specific features described herein, but is intended to cover all substitutions, modifications and equivalents within the scope of the following claims.
I claim:
1. 'I 'he method of creating locally audible sound which comprises: A
phase-modulating a supersonic frequency carrier'signal with an audio frequency signal carrying intelligence to be heard,
acoustically transmitting said phase-modulated supersonic carrier signal at substantially constant amplitude to a region,
and acoustically transmitting a supersonic frequency signal at the resting frequency of the carrier signal and at substantially constant amplitude to a portion of said region where audibility is desired in intersecting relationship with the other acoustically transmitted signal, whereby the resultant of said acoustically transmitted signals produces an audible signal in the region of intersection thereof. 2. The method defined in claim 1, wherein one of said acoustical transmitted signals is transmitted predominantly in one direction.
3. The method defined in claim 1, wherein both of said acoustically transmitted signals are transmitted predominantly in respective different directions. 4. In the method dened in claim 1, the step of eliminating at least most of audio-frequency components from the phase-modulated carrier signal prior to the acoustical transmission thereof.
5. In the method defined in claim 1, the step of varying the amplitude of audible signal by correspondingly varying the amplitude of said audio signal.
6. In the method defined in claim 1, the step of varying the amplitude of the audible signal by varying the amplitude of one of said acoustically transmitted signals.
7. The method of creating locally audible sound which comprises,
flooding an area with a supersonic acoustical signal of a continuously fixed frequency at substantially constant amplitude,
and creating in a portion of said area a supersonic acoustical carrer signal of substantially constant arnplitude having a supersonic resting frequency the same as the fixed frequency of the first acoustical signal but which is phase-modulated by an audio frequency signal bearing intelligence to be heard in said portion of said area.
8. The method of creating locally audible sound which comprises,
tiooding an area with a supersonic acoustical carrier signal of substantially constant amplitude having a supersonic resting frequency which is phase modulated by an audio frequency signal bearing intelligence to be heard,
and creating in a portion of said area where said intelligence is tobe heard a supersonic acoustical signal of substantially constant amplitude at the resting frequency as the carrier signal.
9. A system for producing a locally audible sound signal comprising:
first acoustical transducer means,
means for producing a carrier signal at a supersonic frequency,
means for phase-modulating said carrier signal in accordance with an audio signal bearing intelligence to be heard,
wherein the phase of the carrier signal output of the phase-modulating means is maintained at substantially constant amplitude but is shifted in degree in accordance with the amplitude of said audio frequency signal,AV and in rate according to the frequency of said audio frequency signal,
means for energizing said first transducer means with the phase-modulated signal from said phase-modulating device,
second acoustically transducer means,
and means for energizing said second acoustical transducer means with a supersonic signal of substantially constant amplitude but which is equal in frequency to the resting frequency of the carrier signal,
whereby the first and second transducer means may be disposed to project their acoustical outputs in intersecting relationship in a region where locally audible sound is to be reproduced. 10. The combination claimed in claim 9, and means for filtering out audio frequency components from the output of the phase modulating means.
11. The combination claimed in claim 9, characterized by the fact that the acoustical output at least one of the transducers is predominantly in one direction.
12. The combination claimed in claim 9, characterized by the fact that the acoustical outputs of the transducers are predominantly in respective directions which intersect one another.
13. The combination claimed in claim 9, characterized by the fact that the lirst acoustical transducer means is arranged to fiood an area with the acoustical output thereof and the second transducer means and the means for energizing the same are adapted to be carried upon the person and produce an acoustical signal immediately adjacent said person.
14. A system for producing locally audible sound comprising,
oscillator means for producing a supersonic frequency carrier signal of substantially constant amplitude,
first acoustical transducer means connected to said oscillator means for acoustically transmitting said supersonic carrier signal,
means for producing an audio frequency signal for hearing intelligence to be heard,
phase-shifting means connected to said oscillator means and to the last-named means for phase-shifting said carrier signal in accordance with said audio frequency signal in degree according to the amplitude of said audio frequency signal and in rate corresponding to the frequency of said audio frequency signal and of substantially constant amplitude,
and second acoustical transducer means connected to said phase-shifting means for acoustically transmitting said phase-shifted carrier signal, said first and second acoustical transducer means being so disposed with respect to one another that the acoustical outputs thereof intersect one another in an area where locally audible sound is to be heard.
1S. The combination claimed in claim 14, and filter means connected between said phase-shifting means and the first acoustical transducer means for filtering out audio frequency components from the phase-shifted carrier signal.
References Cited UNITED STATES PATENTS 1,951,669 3/1934 Ramsey l8l-.5 2,345,472 3/ 1944 Goldsmith 181-.5 2,461,344 2/1949 Olson 181-.5
BENJAMIN A. BORCHELT, Primary Examiner.
G. H. GLANZMAN, Assistant Examiner.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US640893A US3398810A (en) | 1967-05-24 | 1967-05-24 | Locally audible sound system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US640893A US3398810A (en) | 1967-05-24 | 1967-05-24 | Locally audible sound system |
Publications (1)
Publication Number | Publication Date |
---|---|
US3398810A true US3398810A (en) | 1968-08-27 |
Family
ID=24570105
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US640893A Expired - Lifetime US3398810A (en) | 1967-05-24 | 1967-05-24 | Locally audible sound system |
Country Status (1)
Country | Link |
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US (1) | US3398810A (en) |
Cited By (37)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3613069A (en) * | 1969-09-22 | 1971-10-12 | Gen Dynamics Corp | Sonar system |
US3612211A (en) * | 1969-07-02 | 1971-10-12 | William T Clark | Method of producing locally occurring infrasound |
WO1998002976A1 (en) * | 1996-07-17 | 1998-01-22 | American Technology Corporation | Directed radiator with modulated ultrasonic sound |
WO1998038833A1 (en) * | 1997-03-02 | 1998-09-03 | Daniel Adir | Voice recording prevention system |
US5859915A (en) * | 1997-04-30 | 1999-01-12 | American Technology Corporation | Lighted enhanced bullhorn |
US5885129A (en) * | 1997-03-25 | 1999-03-23 | American Technology Corporation | Directable sound and light toy |
US5889870A (en) * | 1996-07-17 | 1999-03-30 | American Technology Corporation | Acoustic heterodyne device and method |
US20010007591A1 (en) * | 1999-04-27 | 2001-07-12 | Pompei Frank Joseph | Parametric audio system |
US6285767B1 (en) | 1998-09-04 | 2001-09-04 | Srs Labs, Inc. | Low-frequency audio enhancement system |
US20020118856A1 (en) * | 2001-01-26 | 2002-08-29 | American Technology Corporation | Planar-magnetic speakers with secondary magnetic structure |
US20020126854A1 (en) * | 1997-04-30 | 2002-09-12 | American Technology Corporation | Parametric ring emitter |
US20020191808A1 (en) * | 2001-01-22 | 2002-12-19 | American Technology Corporation | Single-ended planar-magnetic speaker |
US20040114770A1 (en) * | 2002-10-30 | 2004-06-17 | Pompei Frank Joseph | Directed acoustic sound system |
US20050089176A1 (en) * | 1999-10-29 | 2005-04-28 | American Technology Corporation | Parametric loudspeaker with improved phase characteristics |
US20050100181A1 (en) * | 1998-09-24 | 2005-05-12 | Particle Measuring Systems, Inc. | Parametric transducer having an emitter film |
US20050152561A1 (en) * | 2002-01-18 | 2005-07-14 | Spencer Michael E. | Modulator - amplifier |
US20050195985A1 (en) * | 1999-10-29 | 2005-09-08 | American Technology Corporation | Focused parametric array |
US20050248233A1 (en) * | 1998-07-16 | 2005-11-10 | Massachusetts Institute Of Technology | Parametric audio system |
US7031474B1 (en) | 1999-10-04 | 2006-04-18 | Srs Labs, Inc. | Acoustic correction apparatus |
US20060280315A1 (en) * | 2003-06-09 | 2006-12-14 | American Technology Corporation | System and method for delivering audio-visual content along a customer waiting line |
US20070189548A1 (en) * | 2003-10-23 | 2007-08-16 | Croft Jams J Iii | Method of adjusting linear parameters of a parametric ultrasonic signal to reduce non-linearities in decoupled audio output waves and system including same |
US20080022009A1 (en) * | 1999-12-10 | 2008-01-24 | Srs Labs, Inc | System and method for enhanced streaming audio |
US8050434B1 (en) | 2006-12-21 | 2011-11-01 | Srs Labs, Inc. | Multi-channel audio enhancement system |
US8275137B1 (en) | 2007-03-22 | 2012-09-25 | Parametric Sound Corporation | Audio distortion correction for a parametric reproduction system |
US20120281858A1 (en) * | 2011-05-03 | 2012-11-08 | Menachem Margaliot | METHOD AND APPARATUS FOR TRANSMISSION OF SOUND WAVES WITH HIGH LOCALIZATION of SOUND PRODUCTION |
US8767979B2 (en) | 2010-06-14 | 2014-07-01 | Parametric Sound Corporation | Parametric transducer system and related methods |
US8903104B2 (en) | 2013-04-16 | 2014-12-02 | Turtle Beach Corporation | Video gaming system with ultrasonic speakers |
US8934650B1 (en) | 2012-07-03 | 2015-01-13 | Turtle Beach Corporation | Low profile parametric transducers and related methods |
US8958580B2 (en) | 2012-04-18 | 2015-02-17 | Turtle Beach Corporation | Parametric transducers and related methods |
US8988911B2 (en) | 2013-06-13 | 2015-03-24 | Turtle Beach Corporation | Self-bias emitter circuit |
US9036831B2 (en) | 2012-01-10 | 2015-05-19 | Turtle Beach Corporation | Amplification system, carrier tracking systems and related methods for use in parametric sound systems |
US9236842B2 (en) | 2011-12-27 | 2016-01-12 | Dts Llc | Bass enhancement system |
US9258664B2 (en) | 2013-05-23 | 2016-02-09 | Comhear, Inc. | Headphone audio enhancement system |
KR20160043990A (en) | 2013-08-14 | 2016-04-22 | 닛신 세이코 가부시키가이샤 | Al-COATED STEEL SHEET HAVING EXCELLENT TOTAL REFLECTION PROPERTIES AND CORROSION RESISTANCE, AND METHOD FOR MANUFACTURING SAME |
US9332344B2 (en) | 2013-06-13 | 2016-05-03 | Turtle Beach Corporation | Self-bias emitter circuit |
US20190122691A1 (en) * | 2017-10-20 | 2019-04-25 | The Board Of Trustees Of The University Of Illinois | Causing microphones to detect inaudible sounds and defense against inaudible attacks |
EP3523984A4 (en) * | 2016-10-04 | 2020-12-23 | Mohare, Pradnesh | Apparatuses and methods for superposition based wave synthesis |
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US1951669A (en) * | 1931-07-17 | 1934-03-20 | Ramsey George | Method and apparatus for producing sound |
US2345412A (en) * | 1940-12-03 | 1944-03-28 | Earl E Moore | Method of manufacturing billets |
US2461344A (en) * | 1945-01-29 | 1949-02-08 | Rca Corp | Signal transmission and receiving apparatus |
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Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
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US1951669A (en) * | 1931-07-17 | 1934-03-20 | Ramsey George | Method and apparatus for producing sound |
US2345412A (en) * | 1940-12-03 | 1944-03-28 | Earl E Moore | Method of manufacturing billets |
US2461344A (en) * | 1945-01-29 | 1949-02-08 | Rca Corp | Signal transmission and receiving apparatus |
Cited By (68)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3612211A (en) * | 1969-07-02 | 1971-10-12 | William T Clark | Method of producing locally occurring infrasound |
US3613069A (en) * | 1969-09-22 | 1971-10-12 | Gen Dynamics Corp | Sonar system |
US5889870A (en) * | 1996-07-17 | 1999-03-30 | American Technology Corporation | Acoustic heterodyne device and method |
WO1998002976A1 (en) * | 1996-07-17 | 1998-01-22 | American Technology Corporation | Directed radiator with modulated ultrasonic sound |
WO1998038833A1 (en) * | 1997-03-02 | 1998-09-03 | Daniel Adir | Voice recording prevention system |
US5885129A (en) * | 1997-03-25 | 1999-03-23 | American Technology Corporation | Directable sound and light toy |
US5859915A (en) * | 1997-04-30 | 1999-01-12 | American Technology Corporation | Lighted enhanced bullhorn |
US7088830B2 (en) | 1997-04-30 | 2006-08-08 | American Technology Corporation | Parametric ring emitter |
US20020126854A1 (en) * | 1997-04-30 | 2002-09-12 | American Technology Corporation | Parametric ring emitter |
US8027488B2 (en) | 1998-07-16 | 2011-09-27 | Massachusetts Institute Of Technology | Parametric audio system |
US9036827B2 (en) | 1998-07-16 | 2015-05-19 | Massachusetts Institute Of Technology | Parametric audio system |
US20050248233A1 (en) * | 1998-07-16 | 2005-11-10 | Massachusetts Institute Of Technology | Parametric audio system |
US6285767B1 (en) | 1998-09-04 | 2001-09-04 | Srs Labs, Inc. | Low-frequency audio enhancement system |
US20050100181A1 (en) * | 1998-09-24 | 2005-05-12 | Particle Measuring Systems, Inc. | Parametric transducer having an emitter film |
US20010007591A1 (en) * | 1999-04-27 | 2001-07-12 | Pompei Frank Joseph | Parametric audio system |
US7391872B2 (en) | 1999-04-27 | 2008-06-24 | Frank Joseph Pompei | Parametric audio system |
US7031474B1 (en) | 1999-10-04 | 2006-04-18 | Srs Labs, Inc. | Acoustic correction apparatus |
US7907736B2 (en) | 1999-10-04 | 2011-03-15 | Srs Labs, Inc. | Acoustic correction apparatus |
US20060126851A1 (en) * | 1999-10-04 | 2006-06-15 | Yuen Thomas C | Acoustic correction apparatus |
US20050089176A1 (en) * | 1999-10-29 | 2005-04-28 | American Technology Corporation | Parametric loudspeaker with improved phase characteristics |
US8199931B1 (en) | 1999-10-29 | 2012-06-12 | American Technology Corporation | Parametric loudspeaker with improved phase characteristics |
US20050195985A1 (en) * | 1999-10-29 | 2005-09-08 | American Technology Corporation | Focused parametric array |
US7987281B2 (en) | 1999-12-10 | 2011-07-26 | Srs Labs, Inc. | System and method for enhanced streaming audio |
US20080022009A1 (en) * | 1999-12-10 | 2008-01-24 | Srs Labs, Inc | System and method for enhanced streaming audio |
US8751028B2 (en) | 1999-12-10 | 2014-06-10 | Dts Llc | System and method for enhanced streaming audio |
US8953821B2 (en) | 2000-01-14 | 2015-02-10 | Frank Joseph Pompei | Parametric audio system |
US20080285777A1 (en) * | 2000-01-14 | 2008-11-20 | Frank Joseph Pompei | Parametric audio system |
US20020191808A1 (en) * | 2001-01-22 | 2002-12-19 | American Technology Corporation | Single-ended planar-magnetic speaker |
US7142688B2 (en) | 2001-01-22 | 2006-11-28 | American Technology Corporation | Single-ended planar-magnetic speaker |
US20070127767A1 (en) * | 2001-01-22 | 2007-06-07 | American Technology Corporation | Single-ended planar-magnetic speaker |
US20020118856A1 (en) * | 2001-01-26 | 2002-08-29 | American Technology Corporation | Planar-magnetic speakers with secondary magnetic structure |
US20090097693A1 (en) * | 2001-01-26 | 2009-04-16 | Croft Iii James J | Planar-magnetic speakers with secondary magnetic structure |
US20060050923A1 (en) * | 2001-01-26 | 2006-03-09 | American Technology Corporation | Planar-magnetic speakers with secondary magnetic structure |
US6934402B2 (en) | 2001-01-26 | 2005-08-23 | American Technology Corporation | Planar-magnetic speakers with secondary magnetic structure |
US7224219B2 (en) | 2002-01-18 | 2007-05-29 | American Technology Corporation | Modulator-amplifier |
US20070015473A1 (en) * | 2002-01-18 | 2007-01-18 | American Technology Corporation | Modulator-amplifier |
US7109789B2 (en) | 2002-01-18 | 2006-09-19 | American Technology Corporation | Modulator—amplifier |
US20050152561A1 (en) * | 2002-01-18 | 2005-07-14 | Spencer Michael E. | Modulator - amplifier |
US20110044467A1 (en) * | 2002-10-30 | 2011-02-24 | Frank Joseph Pompei | Directed acoustic sound system |
US8538036B2 (en) | 2002-10-30 | 2013-09-17 | Frank Joseph Pompei | Directed acoustic sound system |
US20040114770A1 (en) * | 2002-10-30 | 2004-06-17 | Pompei Frank Joseph | Directed acoustic sound system |
US20060280315A1 (en) * | 2003-06-09 | 2006-12-14 | American Technology Corporation | System and method for delivering audio-visual content along a customer waiting line |
US7564981B2 (en) | 2003-10-23 | 2009-07-21 | American Technology Corporation | Method of adjusting linear parameters of a parametric ultrasonic signal to reduce non-linearities in decoupled audio output waves and system including same |
US20070189548A1 (en) * | 2003-10-23 | 2007-08-16 | Croft Jams J Iii | Method of adjusting linear parameters of a parametric ultrasonic signal to reduce non-linearities in decoupled audio output waves and system including same |
US9232312B2 (en) | 2006-12-21 | 2016-01-05 | Dts Llc | Multi-channel audio enhancement system |
US8509464B1 (en) | 2006-12-21 | 2013-08-13 | Dts Llc | Multi-channel audio enhancement system |
US8050434B1 (en) | 2006-12-21 | 2011-11-01 | Srs Labs, Inc. | Multi-channel audio enhancement system |
US8275137B1 (en) | 2007-03-22 | 2012-09-25 | Parametric Sound Corporation | Audio distortion correction for a parametric reproduction system |
US9002032B2 (en) | 2010-06-14 | 2015-04-07 | Turtle Beach Corporation | Parametric signal processing systems and methods |
US8903116B2 (en) | 2010-06-14 | 2014-12-02 | Turtle Beach Corporation | Parametric transducers and related methods |
US8767979B2 (en) | 2010-06-14 | 2014-07-01 | Parametric Sound Corporation | Parametric transducer system and related methods |
US20120281858A1 (en) * | 2011-05-03 | 2012-11-08 | Menachem Margaliot | METHOD AND APPARATUS FOR TRANSMISSION OF SOUND WAVES WITH HIGH LOCALIZATION of SOUND PRODUCTION |
US9236842B2 (en) | 2011-12-27 | 2016-01-12 | Dts Llc | Bass enhancement system |
US9712916B2 (en) | 2011-12-27 | 2017-07-18 | Dts Llc | Bass enhancement system |
US9036831B2 (en) | 2012-01-10 | 2015-05-19 | Turtle Beach Corporation | Amplification system, carrier tracking systems and related methods for use in parametric sound systems |
US8958580B2 (en) | 2012-04-18 | 2015-02-17 | Turtle Beach Corporation | Parametric transducers and related methods |
US8934650B1 (en) | 2012-07-03 | 2015-01-13 | Turtle Beach Corporation | Low profile parametric transducers and related methods |
US8903104B2 (en) | 2013-04-16 | 2014-12-02 | Turtle Beach Corporation | Video gaming system with ultrasonic speakers |
US9866963B2 (en) | 2013-05-23 | 2018-01-09 | Comhear, Inc. | Headphone audio enhancement system |
US9258664B2 (en) | 2013-05-23 | 2016-02-09 | Comhear, Inc. | Headphone audio enhancement system |
US10284955B2 (en) | 2013-05-23 | 2019-05-07 | Comhear, Inc. | Headphone audio enhancement system |
US9332344B2 (en) | 2013-06-13 | 2016-05-03 | Turtle Beach Corporation | Self-bias emitter circuit |
US8988911B2 (en) | 2013-06-13 | 2015-03-24 | Turtle Beach Corporation | Self-bias emitter circuit |
KR20160043990A (en) | 2013-08-14 | 2016-04-22 | 닛신 세이코 가부시키가이샤 | Al-COATED STEEL SHEET HAVING EXCELLENT TOTAL REFLECTION PROPERTIES AND CORROSION RESISTANCE, AND METHOD FOR MANUFACTURING SAME |
EP3523984A4 (en) * | 2016-10-04 | 2020-12-23 | Mohare, Pradnesh | Apparatuses and methods for superposition based wave synthesis |
US20190122691A1 (en) * | 2017-10-20 | 2019-04-25 | The Board Of Trustees Of The University Of Illinois | Causing microphones to detect inaudible sounds and defense against inaudible attacks |
US10672416B2 (en) * | 2017-10-20 | 2020-06-02 | Board Of Trustees Of The University Of Illinois | Causing microphones to detect inaudible sounds and defense against inaudible attacks |
US11264047B2 (en) | 2017-10-20 | 2022-03-01 | Board Of Trustees Of The University Of Illinois | Causing a voice enabled device to defend against inaudible signal attacks |
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