Method of and apparatus for aiding hearing and the like

• US 3,894,195 A
• Filed: 06/12/1974
• Issued: 07/08/1975
• Est. Priority Date: 06/12/1974
• Status: Expired due to Term

• Current Assignee: Karl D. Kryter
• Original Assignee: Karl D. Kryter
• Inventors: Kryter, Karl D.
• Primary Examiner(s): Blakeslee, Ralph D.
• Application Number:
  US05/478,462
• Time in Patent Office: 391 Days
• Field of Search: 179/17FD,17R,17S,1D,1FS
• US Class Current: 381/23.1
• CPC Class Codes: H04R 25/453 electronically
• CPC Class Codes: H04R 25/502 using analog signal processing

Abstract

This disclosure deals with electronically aiding sensori-neural deafness with frequency-segmented, dynamic range-compressed speech signal processing, wherein noise vs. speech signal discrimination is employed with an optional semi-remote microphone input, and with an optional electronic frequency-shift processing of the signal to prevent or reduce oscillation due to acoustic airborne and/or vibrational feedback between the earphone(s) and the microphone(s).

Claims

1. A method of aiding hearing, that comprises, adjusting the over-all intensity level of speech signals with substantially linear gain over a predetermined range of intensities;

applying the adjusted-intensity signals along a plurality of frequency filtering paths, one passing a broad band of the speech signal frequencies, and the others passing successive adjacent narrow bands within said broad band;

reducing separately in each of the other paths, the dynamic range of intensity levels corresponding to segments of speech signals that vary in intensity for brief moments in the corresponding narrow bandS, as distinguished from the more steady state segments of background noise and steadystate signals; and

combining the signals from said paths.

2. A method as claimed in claim 1 and in which the signals in each of said paths are split and fed along a pair of further paths for right and left ear excitation, with the signal combining step being effectd by combining the right ear further paths and separately combining the left ear further paths.

3. A method as claimed in claim 2 and in which independent level adjustments are effected in each of the further paths prior to such combining.

4. A method as claimed in claim 1 and in which the speech signals are derived from a pair of right and left ear acoustic pick-up regions and a further pick-up region adjustable closer to the source of speech, and then the same are combined prior to said over-all intensity level adjusting step.

5. Hearing aid apparatus having, in combination, microphone pick-up means;

automatic gain control means connected with the pick-up means to adjust the overall signal intensity level of speech signals with substantially linear gain over a predetermined range of intensities;

a plurality of filter paths connected with the automatic gain control means and comprising a first path with broad band filter means for the speech signal frequencies and a plurality of further paths containing band-pass filters of successive adjacent narrow bands within said broad band;

a plurality of speech-noise discrimination means, one connected in each of the plurality of further paths for separately reducing in each path the dynamic range of signal intensity levels corresponding to segments of speech signals that vary in intensity for brief moments in the respective narrow bands, as distinguished from the more steady state segments of background noise and steady-state signals; and

means for combining the signals from said paths.

6. Apparatus as claimed in claim 5 and in which said combining means comprises pairs of right and left ear paths, each pair split from the output of the broad band filter means and the outputs of the plurality of speech-noise discrimination means, with all right ear paths connected together and all left ear paths connected together.

7. Apparatus as claimed in claim 6 and in which said pairs of paths comprise separate variable gain amplifier means and resistive combining networks.

8. Apparatus as claimed in claim 7 and in which further variable gain amplifier means is provided at the output of each of the connected-together right and left ear paths, independently operable with respect to the said separate variable gain amplifier means.

9. Apparatus as claimed in claim 4 and in which each of said speech-noise discrimination means comprises a pair of signal processing paths connected to the corresponding band pass filter means, one of said paths including gating means and attack-release time control means for operating the gating means to apply amplification emphasis along the other processing path for the weaker short-duration segments of the signal relative to the strong intensity segments of the speech signal, but without providing added amplification to relatively low intensity background noise.

10. Apparatus as claimed in claim 4 and in which said microphone pick-up means comprises right and left ear microphones and a remote microphone adjustable to regions closer to the source of speech, with all of the microphones connected to the automatic gain control means.

11. Hearing aid apparatus having, in combination, right and left ear microphone pick-up means, remote microphone means adjustable to regions closer to the source of sound, and common automatic gain control means connected to all of said microphone means to receive the combined inputs thereof.

12. Hearing aid apparatus as claimed in claim 5 and in which frequency shift means is provided connected with the automatic gain control means for shifting the frequency of signals picked up by the microphone pick-up means aNd mechanical vibratory linkages associated therewith, said frequency shift means comprising means for modulating with one frequency and de-modulating with a second and different frequency.