Binaural hearing aid

• US 5,479,522 A
• Filed: 09/17/1993
• Issued: 12/26/1995
• Est. Priority Date: 09/17/1993
• Status: Expired due to Term

• Current Assignee: GN Resound A/S (GN Store Nord A/S)
• Original Assignee: AudioLogic, Inc. (Cirrus Logic Incorporated)
• Inventors: Melanson, John L., Lindemann, Eric
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Le, Huyen D.
• Application Number:
  US08/123,499
• Time in Patent Office: 830 Days
• Field of Search: 381/68, 381/68.2, 381/68.4, 381/97, 381/98, 381/94, 381/104, 381/106, 381/107, 381/60, 381/68.1
• US Class Current: 381/23.1
• CPC Class Codes: G10L 21/0364 for improving intelligibility
• CPC Class Codes: H04R 25/356 Amplitude, e.g. amplitude shift or compression
• CPC Class Codes: H04R 25/505 using digital signal processing
• CPC Class Codes: H04R 25/552 Binaural
• CPC Class Codes: H04R 25/554 using a wireless connection, e.g. between microphone and amplifier or using Tcoils
• CPC Class Codes: H04R 25/558 Remote control, e.g. of amplification, frequency

Abstract

This invention relates to a hearing enhancement system having an ear device for each of the wearer'"'"'s ears, each ear device has a sound transducer, or microphone, and a sound reproducer, or speaker, and associated electronics for the microphone and speaker. Further, the electronic enhancement of the audio signals is performed at a remote digital signal processor (DSP) likely located in a body pack worn somewhere on the body by the user. There is a down-link from each ear device to the (DSP) and an up-link from the DSP to each ear device. The DSP digitally interactively processes the audio signals for each ear based on both of the audio signals received from each ear device. In other words, the enhancement of the audio signal for the left ear is based on the both the right and left audio signals received by the DSP.

In addition digital filters implemented at the DSP have a linear phase response so that time relationships at different frequencies are preserved. The digital filters have a magnitude and phase response to compensate for phase distortions due to analog filters in the signal path and due to the resonances and nulls of the ear canal.

Claims

1. In a binaural hearing enhancement system having a right ear piece with microphone and speaker, a left ear piece with microphone and speaker and a body pack for remote electronics in the system, apparatus for enhancing left and right audio signals comprising:

transceiver means in each ear piece for transmitting right and left input audio signals to the body pack and for receiving right and left output audio signals from the body pack;

stereo transceiver means in the body pack for receiving the right and left input audio signals from the right and left ear pieces and for transmitting right and left output audio signals from the body pack;

left filter means in the body pack for filtering the left input audio signals to compensate for amplitude and phase distortion introduced in audio signals by a left ear microphone or a pre-emphasis filter in the left ear piece;

right filter means in the body pack for filtering the right input audio signals to compensate for amplitude and phase distortion introduced in audio signals by a right ear microphone or a pre-emphasis filter in the right ear piece; and

each of left and right filter means generating a flat, linear-phase, frequency response for the left and right input audio signals in order to deliver undistorted amplitude and phase-aligned left and right signals as left and right distortion-free signals to enhancing means whereby the left and right distortion-free signals accurately reflect interaural amplitude differences and delay differences at the ears;

means for enhancing each of the left and right distortion-free signals based on audio information derived from both the left and right distortion-free signals to produce enhanced left and right output audio signals for transmission to the ear pieces.

2. The system of claim 1 wherein said enhancing means comprises:

means responsive to the left and right distortion-free signals for reducing the noise in each of the left and right signals based on the amplitude and phase differences between the left and right audio signals to produce directional sensitive noise reduced left and right output audio signals for transmission to the right and left ear pieces.

3. The system of claim 2 wherein a user of the hearing aid has predetermined audio requirements for hearing enhancement and said enhancing means further comprises:

means responsive to noise reduced left and right audio signals for compressing the dynamic range of audio signals and for adjusting the left and right audio signals to match the audio requirements of a user of the hearing enhancement system.

4. The system of claim 2 wherein said enhancing means further comprises:

means responsive to the left and right distortion-free signals for reducing the noise in each of the left and right signals based on the short term amplitude deviation from long term average and the pitch in both the left and right distortion-free signals.

5. The apparatus of claim 1 and in addition:

second left filter means for filtering the noise reduced left output audio signal to cancel the effect of left ear resonances and nulls and left ear speaker amplitude and phase distortions;

second right filter means for filtering the noise reduced right output audio signal to cancel the effect of right ear resonances and nulls and right ear speaker amplitude and phase distortions; and

each of said second left and right filter means generating a flat, linear-phase, frequency response for the noise reduced left and right output audio signals at the left and right ears.

6. The apparatus in claim 1 and in addition:

compression means in each ear piece for compressing the dynamic range of the audio signal before the audio signal is transmitted by the transceiver in the ear piece; and

expanding means in said compensating means for restoring the dynamic range of the left and right audio signals received from the ear piece.

7. The apparatus of claim 6 and in addition:

second left filter means for filtering the noise reduced left audio signal to cancel the effect of ear resonances and nulls and left ear speaker amplitude and phase distortions;

second right filter means for filtering the noise reduced right audio signal to cancel the effect of ear resonances and nulls and right ear speaker amplitude and phase distortions;

each of said second left and right filter means generating a flat, linear-phase, frequency response for the noise reduced left and right audio signals at the left and right ears.

8. The apparatus of claim 7 and in addition:

compression means in the body pack for compressing in the dynamic range of the noise reduced left and right audio signal before the noise reduced audio signals are transmitted by transceivers in the body pack to each ear piece; and

expanding means in each of the ear pieces for restoring the dynamic range of the noise reduced left and right audio signals received from the ear pieces.

9. Binaural, digital, hearing aid apparatus comprising:

right ear piece means for mounting microphone means for detecting sound and producing a right ear, electrical, audio signal, a speaker means for reproducing sound from a right ear, electrical, enhanced audio signal, left ear transmitter means for transmitting the right ear audio signal as radiant energy and left ear receiver means for receiving radiant energy transmission of the right ear enhanced audio signal;

left ear piece means for mounting microphone means for detecting sound and producing a left ear, electrical, audio signal, a speaker means for reproducing sound from a left ear, electrical, enhanced audio signal, left ear transmitter means for transmitting the right ear audio signal as radiant energy and left ear receiver means for receiving radiant energy transmission of the right ear enhanced audio signal;

remote means for receiving the left and right audio signals, enhancing the left and right audio signals, and transmitting the enhanced left and right audio signals;

said remote means having means for converting the received left and right audio signals into left and right digital data;

means for compensating the left and right digital data for phase and amplitude distortions in the received left and right audio signals to produce distortion-free left and right digital data that preserves amplitude and phase differences between the left and right audio signals;

means for digitally processing the distortion-free left and right digital data interactively with each other to produce enhanced digital left and right data; and

means for converting the enhanced digital left and right data into the left and right enhanced audio signals for transmission by said remote means.

10. The hearing aid apparatus of claim 9 wherein said digital processing means comprises:

means responsive to the distortion-free left and right digital data for reducing the directional-sensitive noise in the left and right digital data based on the amplitude and phase differences in the left and right audio signals.

11. The hearing aid apparatus of claim 10 wherein said digital processing means further comprises:

means responsive to the distortion-free left and right digital data signals for reducing the noise in each of the left and right digital data signals based on the short term amplitude deviation from long term average and pitch in both the left and right distortion-free digital data signals.

12. In a binaural hearing enhancement system having a right ear piece, a left ear piece and an audio signal processor for processing left and right audio signals in the system, apparatus for enhancing the left and right audio signals comprising:

microphone and electronic means in each ear piece for producing an input audio signal from sound arriving at the ear piece;

speaker and electronic means in each ear piece for producing sound from an output audio signal from the audio signal processor;

left filter means in the audio signal processor for filtering the left input audio signals to compensate for amplitude and phase distortion introduced in audio signals by the microphone and electronic means in the left ear piece;

right filter means in the remote electronics for filtering the right input audio signals to compensate for amplitude and phase distortion introduced in audio signals by the microphone and electronic means in the right ear piece; and

each of left and right filter means generating a flat, linear-phase, frequency response for the left and right input audio signals in order to provide undistorted amplitude and phase-aligned left and right signals as left and right distortion-free signals whereby the left and right distortion-free signals accurately reflect interaural amplitude differences and delay differences at the ears;

means for enhancing each of the left and right distortion-free signals based on audio information derived from both the left and right distortion-free signals to produce enhanced left and right output audio signals for the left and right ear pieces, respectively.

13. The system of claim 12 wherein said enhancing means comprises:

means responsive to the left and right distortion-free signals for reducing the noise in each of the left and right signals based on the amplitude and phase differences between the left and right audio signals to produce directional-sensitive noise reduced left and right output audio signals for the right and left ear pieces.

14. The system of claim 13 wherein a user of the hearing aid has predetermined audio requirements for hearing enhancement and said enhancing means further comprises:

means responsive to noise reduced left and right audio signals for compressing the dynamic range of audio signals and for adjusting the left and right audio signals to match the audio requirements of a user of the hearing enhancement system.

15. The system of claim 12 wherein said enhancing means further comprises:

means responsive to the left and right distortion-free signals for reducing the noise in each of the left and right signals based on the short term amplitude deviation from long term average and the pitch in both the left and right distortion-free signals.