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Publication numberUS2043416 A
Publication typeGrant
Publication dateJun 9, 1936
Filing dateMar 8, 1934
Priority dateJan 27, 1933
Publication numberUS 2043416 A, US 2043416A, US-A-2043416, US2043416 A, US2043416A
InventorsLueg Paul
Original AssigneeLueg Paul
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Process of silencing sound oscillations
US 2043416 A
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Description  (OCR text may contain errors)

Patented June 9, 1936 PROCESS OF SILENCING SOUND OSCILLA TIONS Paul Lueg, Kirchstrasse, Germany Application March 8, 1934, Serial No. 714,582 In Germany January 27, 1933' 4 Claims.

In the known processes of silencing sound oscillations the silencing is effected by subjecting these oscillations to a displacement of phases, but in these processes only the source of the oscillations is used to cause the displacement of phases, so that the superposition of phasestakes place in a purely mechanical manner.

The present invention does away with these drawbacks and relates to a process of silencing sound oscillations especially of a disturbing nature, which can be employed independently of the source of oscillation. According to the present invention the sound oscillations, which are to be silenced are taken in by a receiver and reproduced by a reproducing apparatus in the form of sounds having an opposite phase. The means of carrying out said processes consist preferably of electrical apparatus and the reception is efiected by amicrophone, by which the acoustic oscillations are transformed into electric ones. The microphone is connected over an amplifier with a reproducing apparatus (loudspeaker). The phase opposition can be efiected by several means. In case for instance of only one single tune moving in one well defined direction (in a pipe for instance) the phase opposition can be efieeted in a very simple manner by adjusting the distance between the microphone and the producing apparatus. In this case the microphone is preferably placed between the sound source and the reproducing apparatus causing the sound oscillations to meet first the microphone and then the reproducing apparatus. Consequently two difierent kinds of oscillations are present in the reproducing apparatus, the one representing the sound oscillation of the tune, moving with normal soundvelocity, the other representing a wave advanced with respect to the first wave by electrical means between the microphone and the reproducing apparatus and reproduced by the reproducing apparatus. The phase opposition can be efiected by suitably adjusting the distance between themicrophone and the reproducing apparatus.

In order to silence acoustic vibrations of any shape within a certain range, the microphone and loudspeaker are suitably placed close to each other in such a way that the oscillations coming from a certain point will meet the microphone a silencing of the noise is effected within the range of the reproducer. Preferably one side of the loudspeaker diaphragm is used for it, whereas the other side is silenced.

It is to be understood of course that in the 5 same way several receiving and reproducing apparatus can be used working either in a single way or in connection with each other.

Sometimes it will be necessary not to silence all the noise oscillations but only a part of them. This will be the case when for instance disagreeable secondary (stray) noises (see further below) for instance in theaters, concert halls, etc. have to be avoided. In the same way is this the case in ofiices in which the disagreeable noise of the type writing machines has to be silenced. This can be efiected in a very simple way in accordance with the invention by taking in well defined frequencies of the sound oscillations, by displacing the phases and reproducing same thereupon.

In the specification only the outstanding features of the process are stated and the means of the process may be modified by a more refined working out of the problem. The electric reception and the transforming of the acoustic oscillations have the advantage of an extraordinarily exact reproduction, so that a much more exact and more sudden silencing of the oscillations can be obtained than by the mechanical process. The process on the whole'can be employed in solid as well as in liquid and in gaseous sound carriers.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawing showing by way of example preferred embodiments of the inventive idea.

In the drawing:--

Figure 1 illustrates diagrammatically means of silencing a single linear sound wave.

Figure 2 illustrates diagrammatically a plurality of sound waves and means for silencing or damping the same.

Figure 3 is a diagram illustrating the sound waves.

Figure 4 illustrates diagrammatically means for silencing spatial sound waves.

Figure 1 illustrates a simple device by means of which a single predetermined tone which comes from a predetermined direction is silenced or damped within a pipe T. This sound or tone is actually a sine-like sound wave and is to be silenced or damped by a sound Wave having an opposite phase. This sound of opposite phase is produced simply by adjusting the distance between the microphone M, which is built into the pipe T and the sound reproducing device or loudspeaker L. The microphone is situated between the source of the sounds and the loudspeaker. Therefore, the sound waves s arriving from the point A first strike the microphone andthen the loudspeaker. The sound wave received by the microphone is transmitted electrically with the assistance of the amplifier E to the loudspeaker. Naturally this electrically transmitted sound wave is advanced in relation to the sound wave s which moves with a normal velocity of sound.

The extent of this advancement of the electrically transmitted sound wave can be conveniently adjusted by adjusting the distance between the microphone and the loudspeaker. It is easily possible to determine and regulate the distance between the microphone and the loudspeaker in such manner that the sound wave s which is electrically reproduced by the loudspeaker has an opposite phase from the original natural sound wave 8 Therefore, due to this creation'of a sound wave having an opposite phase, the two sound waves will silence each other or dampen each other.

Figure 2 shows a sound source A which, for

instance, is situated in open space, so that it emits sound waves traveling in all directions. In that case the microphone M and the loudspeaker L are both placed at the same distance from the source A and are electrically interconnected by means of an amplifier V. 7, Sound waves (11 and an produced by the source A strike the microphone M and the loudspeaker L, respectively. The sound wave in striking the microphone M is reproduced by the loudspeaker L in an opposite phase. This changing of the phase may be accomplished by several well known methods, for instance, by changing the poles of the loudspeaker L, or by providing a transformer (not shown) between the loudspeaker L and the microphone M. The sound waves produced by the sound source A are silenced around the loud.- speaker L by sound waves having an opposite phase produced by the loudspeaker L.

The sound waves which-do not have a sine-like form, 1. e., noises, may be represented by the irregular curve G G, which is shown in Figure 3. Naturally an exact phase opposition cannot be produced by shifting a sound wave of this type by 180, since the two halves of the curve are entirely different one from the other. In that case the phase opposition is produced by the following means. In my present invention, I employ the principle that an ordinary oscillating membrane of a loudspeaker provided with fiat surfaces oi. the type employed in the usual surface loudspeaker, creates thickenings and thinnings of the air when a sound is reproduced. In the example illustrated in Figure 4, the noise emerging from the point A reaches the microphone M situated at a distance a from the point A. The microphone M transmits this noise electrically to the loudspeaker in such manner that an opposite wave is produced, such as shown in Figure 3. This means that each time when a thickening of the air meets the microphone the loudspeaker answers by a corresponding thinning of the air and vice versa.

Due to this arrangement, phase opposition is produced within the space B, mainly in the direction of the arrow B.

What I claim is:

1. In combination, means receiving sound oscillations travelling in the air and means reproducing sound oscillations within the field of action of the first-mentioned sound oscillations and causing them to travel substantially-in the same direction as that of the first-mentioned sound oscillations, the second-mentioned sound oscillations having an opposite phase in relation to the first-mentioned sound oscillations, whereby the received sound oscillations are silenced within the.

range of the reproduced sound oscillations.

- 2. A process of silencing sound oscillations comprising receiving a sound wave travelling through the air, causing said sound wave to produce electricaloscillations, and transforming said electrical oscillations into a sound wave having an opposite phase to the received sound wave and travelling through the air substantially in the direction of the received sound wave, whereby the received sound wave is silenced within the range of the second-mentioned sound wave. 1

3. In combination, a microphone for receiving a sound wave travelling through the air in substantially one direction, an amplifier electrically connected with said microphone, and means electrically connected with said amplifier for transforming electrical oscillations caused by said sound wave into another sound wave traveling through the air'substantially in the same direction as-the received sound wave, the distance between said microphone and said means being adjustable to cause a mutual elimination of the two sound waves within the field of action of the received sound wave.

4. In combination with a source of sound waves travelling through the air; a microphone adapted to receive sound waves emitted by said source and situated at a certain distance from said source, and a loudspeaker electrically connected with said microphone and situated at the same distance from said source, said loudspeaker producing sound waves having an opposite phase to the received sound waves and travelling through the air substantially in the same direction as the received sound waves, whereby the receivedsound waves are eliminated within the field of action of the sound waves produced by the loudspeaker.

PAUL LUEG.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2431862 *Mar 26, 1946Dec 2, 1947Sperry Prod IncMeans for supersonic inspection
US2516776 *Aug 7, 1946Jul 25, 1950Bell Telephone Labor IncElectroacoustic system and means
US2611035 *Jan 31, 1950Sep 16, 1952Rca CorpNoise-canceling microphone
US2694868 *Aug 3, 1943Nov 23, 1954Mcmillan Edwin MEcho repeater
US2776020 *Feb 9, 1955Jan 1, 1957Gen ElectricNoise reducing system for transformers
US2783008 *Jul 28, 1951Feb 26, 1957Jr Albert G BodineAcoustical boundary layer control for aerodynamic bodies
US2966549 *Apr 2, 1954Dec 27, 1960Lawrence J FogelApparatus for improving intelligence under high ambient noise levels
US2972018 *Nov 30, 1953Feb 14, 1961Rca CorpNoise reduction system
US2983790 *Apr 30, 1953May 9, 1961Rca CorpElectronic sound absorber
US3044570 *Apr 2, 1958Jul 17, 1962Watts Ltd Cecil ELoudspeakers
US3071752 *Jan 2, 1958Jan 1, 1963Strasberg MurrayInterference reduction apparatus
US3229429 *Apr 27, 1960Jan 18, 1966Willard Conrad IvanSecure conference systems
US3308425 *Sep 3, 1965Mar 7, 1967Vector Cable CompanyDepth sensitive transducer
US3685610 *Feb 10, 1971Aug 22, 1972Messerschmitt Boelkow BlohmNoise reduction for propellers
US3826870 *Mar 20, 1970Jul 30, 1974Quest Electronics CorpNoise cancellation
US3936606 *Dec 11, 1972Feb 3, 1976Wanke Ronald LAcoustic abatement method and apparatus
US4044203 *Aug 25, 1975Aug 23, 1977National Research Development CorporationActive control of sound waves
US4109108 *Sep 7, 1977Aug 22, 1978National Research Development CorporationAttenuation of sound waves in ducts
US4473906 *Dec 5, 1980Sep 25, 1984Lord CorporationActive acoustic attenuator
US4805733 *Jul 7, 1987Feb 21, 1989Nippondenso Co., Ltd.Active silencer
US4989252 *Sep 28, 1989Jan 29, 1991Kabushiki Kaisha ToshibaSilencer
US5040156 *Jun 29, 1990Aug 13, 1991Battelle-Institut E.V.Acoustic sensor device with noise suppression
US5088575 *Sep 13, 1990Feb 18, 1992Nelson Industries, Inc.Acoustic system with transducer and venturi
US5117642 *Dec 14, 1990Jun 2, 1992Kabushiki Kaisha ToshibaLow noise refrigerator and noise control method thereof
US5127235 *Dec 14, 1990Jul 7, 1992Kabushiki Kaisha ToshibaLow noise refrigerator and noise control method thereof
US5255321 *Dec 5, 1990Oct 19, 1993Harman International Industries, Inc.Acoustic transducer for automotive noise cancellation
US5347585 *Sep 10, 1991Sep 13, 1994Calsonic CorporationSound attenuating system
US5355417 *Oct 21, 1992Oct 11, 1994The Center For Innovative TechnologyActive control of aircraft engine inlet noise using compact sound sources and distributed error sensors
US5475761 *Jan 31, 1994Dec 12, 1995Noise Cancellation Technologies, Inc.Adaptive feedforward and feedback control system
US5488666 *Oct 1, 1993Jan 30, 1996Greenhalgh TechnologiesSystem for suppressing sound from a flame
US5662136 *Sep 11, 1995Sep 2, 1997Defense Research Technologies, Inc.Acousto-fluidic driver for active control of turbofan engine noise
US6155111 *Sep 23, 1998Dec 5, 2000Audi AgWind tunnel with air vibration phase cancellation
US6461144 *May 5, 2000Oct 8, 2002Alstom (Switzerland) LtdMethod of controlling thermoacoustic vibrations in a combustion system, and combustion system
US6622647Jun 26, 2001Sep 23, 2003Depoy Martin L.Active noise cancellation for a torpedo seeker head
US6671224 *Aug 26, 2002Dec 30, 2003Schlumberger Technology CorporationActive reduction of tool borne noise in a sonic logging tool
US7088828 *Apr 13, 2000Aug 8, 2006Cisco Technology, Inc.Methods and apparatus for providing privacy for a user of an audio electronic device
US7267196 *Feb 12, 2004Sep 11, 2007The Boeing CompanyMethod and apparatus for reducing acoustic noise
US7423520Mar 2, 2004Sep 9, 2008Tdk CorporationNoise suppressing circuit
US8077489May 15, 2008Dec 13, 2011Lockheed Martin CorporationSystem and method of cancelling noise radiated from a switch-mode power converter
US8155332 *Jan 10, 2008Apr 10, 2012Oracle America, Inc.Method and apparatus for attenuating fan noise through turbulence mitigation
US8369536Nov 13, 2008Feb 5, 2013Korea Advanced Institute Of Science And TechnologySound system, sound reproducing apparatus, sound reproducing method, monitor with speakers, mobile phone with speakers
DE2712534A1 *Mar 22, 1977Sep 28, 1978Sound Attenuators LtdVerfahren und vorrichtung zur aktiven schalldaempfung
DE4033269A1 *Oct 19, 1990Apr 23, 1992Gillet Heinrich GmbhSchalldaempferanlage fuer kraftfahrzeuge
DE4130559A1 *Sep 13, 1991Mar 25, 1993Calsonic CorpSilencing system with expansion chamber formed in main pipe - incorporates combination of active and passive reflecting surfaces in pipes of different dia.
DE19702390A1 *Jan 24, 1997Jul 30, 1998Audi Nsu Auto Union AgWindkanal
EP0040462A1 *Feb 18, 1981Nov 25, 1981Bose CorporationElectroacoustical audible noise reducing apparatus
EP0611089A2 *Feb 2, 1994Aug 17, 1994DIGISONIX, Inc.Active acoustic control system matching model reference
EP2645362A1May 25, 2012Oct 2, 2013Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.Apparatus and method for improving the perceived quality of sound reproduction by combining active noise cancellation and perceptual noise compensation
WO2013076137A1Nov 21, 2012May 30, 2013Renault S.A.S.Method and device for controlling an active noise reduction system
Classifications
U.S. Classification381/71.1, 415/119, 181/197, 367/1, 181/207
International ClassificationF01N1/06, G10K11/178, F16L55/033
Cooperative ClassificationG10K2210/3044, G10K2210/3216, G10K11/1782, F16L55/0333, G10K2210/508, F01N1/065, G10K2210/3217, G10K2210/3011
European ClassificationF01N1/06B, G10K11/178B, F16L55/033G