5,265,168

43.66.Ts HEARING AID

Hans-Rudolf Schiess and Benno Moser, assignors to Siemens Aktiengesellschaft

23 November 1993 (Class 381/69); filed in European Patent Office 18 December 1990

The patent shows a method of interconnecting hearing aid compo- nents that greatly decreases the amount of soldering required and simpli- fies servicing. The critical element is an anisotropic electrically conductive layer-shaped member formed of an electrically insulating matrix material having electrically conductive fibers that are aligned perpendicularly to the plane of the layer and uniformly distributed. Connection is made between various pairs of oppositely located contacts by squeezing the layer, for example, by screwing the back on the case. Various places in the hearing aid where the material can be used are shown.--SFL

5,266,919

43.66.Ts TONE GENERATOR FOR USE WITH

HEARING AIDS

Perry R. Cook, Palo Alto, California and Leo Boyd, Campbell, California

30 November 1993 (Class 340/384 E); filed I April 1991

The patent describes a battery-operated programmable tone gener- ator that allows a hearing aid wearer to set the gain of the hearing aid to a prescribed level. The device is hand-held at arms length to obtain re- peatable results. Digitally controlled analog circuitry produces pairs of tone bursts that bracket the desired volume control setting of the hearing aid.--SFL

5,195,140

43.72.Ar ACOUSTIC SIGNAL PROCESSING

APPARATUS

Masaki Kudo et aL, assignors to Yamaha Corporation 16 March 1993 (Class 381/71); filed in Japan 5 January 1990

Certain applications of feedback (infinite impulse response) digital filters are particularly sensitive to the limit-cycle behavior these filters can exhibit. A variety of numerical techniques has been proposed to minimize or eliminate limit-cycle patterns. The approach disclosed here is to run multiple copies of the filter, each with a different phase, and then average

INPUT

OUTPUT

,•, sI2 B

/ S02

LC20

P samples

sssx G

P samples

•l•lslsl ...... Islslsl x • G+I A

c s.s.s.

P combined samples

accomplish the desired rate change, but with an interpolation scheme that results in smoother transitions. The device includes provisions for AD- PCM compression of original or rate-altered speech.--DLR

5,195,168

43.72.Gy SPEECH CODER AND METHOD HAVING SPECTRAL INTERPOLATION AND FAST

CODEBOOK SEARCH

Mei Yong, assignor to Codex Corporation 16 March 1993 (Class 395/2); filed 15 March 1991

This code-excited linear prediction (CELP) vocoder uses a spectral interpolation technique to speed up the codebook search operation. The LPC coefficients are interpolated between adjacent frames or subframes and autocorrelations are computed with the latest uninterpolated coefE- cient set. These results somehow improve the codebook search. I look forward to the day when patents will be written by computers instead of by lawyers.--DLR

5,226,083

43.72.Gy COMMUNICATION APPARATUS FOR SPEECH SIGNAL

Tetsu Taguchi, assignor to NEC Corporation 6 July 1993 (Class 381/36); filed in Japan I March 1990

This speech signal encrypter is based on LPC methods, coding the residual and coefficient vectors separately. An additional trick is that the residual is altered before transmission by removing less significant fre- quency components, then rearranging the frequency scale of the remain- ing signal.•DLR

the results. In certain cases, two filters can be set to cancel but, in general, it seems like an expensive way to get a few more bits of word length in the multiplier hardware.mDLR

5,216,744

43.72.Ew TIME SCALE MODIFICATION OF SPEECH SIGNALS

Charles C. Alleyne and Kevin J. Bruemmer, assignors to Dictaphone Corporation

I June 1993 (Class 395/2); filed 21 March 1991

This speech rate changer uses the outputs of a variety of independent fundamental frequency estimators to determine the most likely interval during voiced speech. Periods are deleted or duplicated as required to

5,226,084

43.72.Gy METHODS FOR SPEECH QUANTIZATION AND ERROR CORRECTION

John C. Hardwick and Jae S. Lim, assignors to Digital Voice Systems, Incorporated

6 July 1993 (Class 381/41); filed 5 December 1990

This vocoder is based on a new speech coding method referred to in the patent as multi-band excitation. The MBE system uses a fixed number of bits to code a set of spectral amplitudes and phases for each speech frame. The bit allocation strategy considers both spectral shape within a frame and a change from one frame to the next using a cosine transform of the residual as an indicator.--DLR

3687 J. Acoust. Soc. Am., Vol. 95, No. 6, June 1994 Reviews of Acoustical Patents 3687

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