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Publication numberUS3098121 A
Publication typeGrant
Publication dateJul 16, 1963
Filing dateSep 15, 1958
Priority dateSep 15, 1958
Publication numberUS 3098121 A, US 3098121A, US-A-3098121, US3098121 A, US3098121A
InventorsWadsworth William B
Original AssigneeDavid Clark Company Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Automatic sound control
US 3098121 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)



ATTORNEY United States Patent "ice 3,098,121 AUTOMATIC SOUND CONTROL William B. Wadsworth, Concord, Mass., assignor to David Clark Company Incorporated, Worcester, Mass., a corporation of Massachusetts Filed Sept. 15, 1958, Ser. No. 761,217 1 Claim. (Cl. 179-1) This invention relates to a unique application of automatic control of sound in a noisy location. The prior art utilizes the principle that where a public address system is used in a noisy location, a constant signal to noise ratio can be approximated if a sampling microphone is used to produce a control signal for the amplifier in the public address system, whereby the sound power output is increased in proportion to the increase in the local interfering noise. A fundamental difiiculty lies in the fact that the sampling microphone picks up both sound and desired signal, and some differentiating means is required. Many schemes have been proposed in the prior art with varying success.

In the present invention this problem does not exist over the range of sound signal required, and therefore this invention is simple and more effective. The principal application for this new method is in noisy environments where the operator is using earphones such as in jet airplane ground crews, etc., Where a desired signal or sound is transmitted to the listener through the earphones which are themselves shielded from the ambient noises by means as described in prior pending applications, erg, S.N. 597,161, filed July 11, 1956 and 603,111 filed August 9, 1956, now Patent Numbers 2,899,683 and 2,981,958 respectively.

The principal object of the present invention resides in the provision of devices such as ear protectors, including earphones, which are adapted to protect the ears of the user from a high noise level which is not desired to impinge upon the ears of the user, and including a sampling device and an electronic control for the loudness of the signal impressed upon the earphones. The sampling device samples the ambient local surrounding atmosphere for increase and decrease in unwanted sounds, and the electronic system is controlled by the sampling device to increase and decrease substantially proportionately the ear phone signal in the ear protector, whereby the user automatically hears wanted signals from a distance at approximately the same sound level regardless of the increase and decrease in the unwanted loudness of the sound level surrounding the user and the earphones which he is using.

Other objects and advantages of the invention will appear hereinafter.

Reference is to be had to the accompanying drawings, in which FIG. 1 is a view illustrating the present device;

-FIG. 2 is a diagrammatic view showing the system; and

FIG. 3 is an electronic diagram showing the details of the system.

In carrying out the present invention, there is provided a set of ear protectors which may be such as are described in copending application Serial No. 495,394, filed March 21, 1955, now Patent No. 2,946,862. These ear protectors are provided with phones 12, 12. These phones and ear protectors are not a part of the present invention except as part of the combination, and it is believed that they do not need to he further described. However, these earphones are connected into the sampling and control device which is indicated in this case as being in a housing 14 and may be mounted on the headband 16, 16. The sampling device is provided with a sampling microphone and it is to be understood that the wanted signal feeds into the ear protector by well known means, and thence feeds to the earphones, so that the user receives all his I 341 925,121 Patented July 16, 1963 information from a remote point while his ears are at the same time effectively protected against the deleterious effects of high sound energy existing locally in the atmosphere surrounding the user. In this way the operator is apprised of information he needs in spite of the high level of noise surrounding him.

Referring now to FIG. 2, it will be seen that the speech input or desired signal is impressed upon amplifier A which then is transferred to the variable gain amplifier B and thence to the speech output at C which is of course the earphones 12. Without the present invention, the loudness of the speech output at C (or earphones '12, 12) depends only on the origin of the signal, and the signal level to the user therefore depends solely on the ambient noise level. Total signal-to-ambient-noise ratio tends to rise and fall, making for less intelligible speech, in the absence of means for causing the loudness of the speech output to rise and fall with the rise and fall of the ambient noise.

The sampling microphone is shown as at D in the diagram of FIG. 2, and also in FIG. 1. This microphone is in constant communication with amplifier E and this microphone signal is then transferred to the rectifier P which then controls the variable gain amplifier B to increase or decrease the level of loudness and speech output at C, depending upon the signal received by the sampling microphone at C.

A circuit for carrying out this effect is shown in FIG. 3 wherein the connections are as indicated and the various elements are as follows:

Also affects It is believed from the foregoing that the use and operation of this invention will be apparent. The device provides an automatic amplifier for desired signal which is to be impressed on a protected ear-phone from a remote point, whenever the noise level increases in the surrounding atmosphere as respects the user of the device. Therefore regardless of the ambient noise level, the desired signal through the ear-phones comes in on a level which is intelligible to the operator at all times. The strength of the signal at the ear-phones can be varied by varying the values of portions of the circuit but in general the variation of increase of signal at the phones will be more or less proportional to the increase in ambient noise level although this proportion may be varied to suit special conditions.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claim, but what I claim is:

Audio communication apparatus with volume control operated by ambient noise; comprising in combination an ear protector shell adapted to be applied to the head of a user against the users ear, support means for retaining said shell in position on the users head, said shell having relatively high attenuation of exterior sound Waves and ambient noise, a transducer mounted in said shell for communicating wanted sound to the users ear as the function of an electrical signal applied to the transducer, means for picking up wanted sound and transforming the same into an electrical signal, a variable gain amplifier connected to said Wanted sound pick up means and to said transducer for applying to the latter a signal of a variable gain, a sampling microphone mounted on said support means for picking up unwanted ambient noise, second am plifying means connected to said microphone, and recti- References Cited in the file of this patent UNITED STATES PATENTS 2,501,327 Good Mar. 21, 1950 2,891,116 Nichols June 16, 1959 2,946,862 Wadsworth et a1. July 26, 1960 2,972,018 Hawley et a1 Feb. 14, 1961 OTHER REFERENCES Electronic Control of Noise Vibration and Reverberation, by Olson, Journal of the Acoustical Society of America, vol. 28, No. 5, September 1956 (Reprint by RCA Labs).

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2501327 *Dec 6, 1946Mar 21, 1950Rca CorpNoise operated automatic volume control
US2891116 *Mar 4, 1955Jun 16, 1959Nichols & Clark IncHearing aid device
US2946862 *Mar 21, 1955Jul 26, 1960David Clark Company IncEar protector and communication equipment
US2972018 *Nov 30, 1953Feb 14, 1961Rca CorpNoise reduction system
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3306991 *Jun 4, 1963Feb 28, 1967Homer J WoodProtective hearing aid
US3394226 *Aug 19, 1963Jul 23, 1968Daniel E. Andrews Jr.Special purpose hearing aid
US4132861 *Jul 27, 1977Jan 2, 1979Gentex CorporationHeadset having double-coil earphone
US4307385 *Nov 22, 1978Dec 22, 1981Sue Ann EvansNoise monitoring apparatus
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US4546215 *Oct 7, 1983Oct 8, 1985Ferraro Michael VDetachable earmuffs for headsets
US5239588 *Dec 18, 1989Aug 24, 1993Davis Murray AHearing aid
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US6078672 *May 6, 1997Jun 20, 2000Virginia Tech Intellectual Properties, Inc.Adaptive personal active noise system
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US6420975Dec 17, 1999Jul 16, 2002Donnelly CorporationInterior rearview mirror sound processing system
US6594367Oct 25, 1999Jul 15, 2003Andrea Electronics CorporationSuper directional beamforming design and implementation
US6801629 *Dec 22, 2000Oct 5, 2004Sonic Innovations, Inc.Protective hearing devices with multi-band automatic amplitude control and active noise attenuation
US6888950Jul 2, 2002May 3, 2005Jovid Designs, LlcEar warming article including electronic device and easily interchangeable advertising areas
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US7110551Mar 27, 2000Sep 19, 2006Adaptive Technologies, Inc.Adaptive personal active noise reduction system
US7542575Feb 7, 2005Jun 2, 2009Donnelly Corp.Digital sound processing system for a vehicle
US7668330Nov 29, 2004Feb 23, 2010David R. SiskinEar warming article including electronic device and easily interchangeable advertising areas
US7853026May 28, 2009Dec 14, 2010Donnelly CorporationDigital sound processing system for a vehicle
US8204265Jan 5, 2010Jun 19, 2012David R. SiskinEar warming article including electronic device and easily interchangeable advertising areas
US8625815Dec 8, 2010Jan 7, 2014Donnelly CorporationVehicular rearview mirror system
US9434314Jan 6, 2014Sep 6, 2016Donnelly CorporationElectronic accessory system for a vehicle
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U.S. Classification381/72
International ClassificationH03G3/32
Cooperative ClassificationH03G3/32
European ClassificationH03G3/32