Mitigating acoustic feedback in hearing aids with frequency warping by all-pass networks

Patent metadata

Field	Value
Publication number	US-11849283-B2
Application number	US-202017760842-A
Country	US
Kind code	B2
Filing date	Sep 16, 2020
Priority date	Sep 16, 2019
Publication date	Dec 19, 2023
Grant date	Dec 19, 2023

Abstract

A method and system or device such as a hearing aid are provided for processing audio signals. In accordance with the method, an audio signal is received and divided into a plurality of frequency sub-bands. For each of the frequency sub-band signals, the signal is further divided into overlapping temporal frames. Each of the temporal frames are windowed. Frequency warping is performed on each of the windowed frames. Overlap-and-add is performed on the frequency warped frames. The frequency warped sub-bands are combined into a full band to provide a frequency warped signal.

First claim

The invention claimed is:

1. A method for processing sub-band audio signals, comprising:
receiving an audio signal;
dividing the audio signal into overlapping temporal frames;
windowing each temporal frame;
time-reversing the windowed temporal frames;
for each of the time-reversed windowed temporal frames, passing the time-reversed temporal frame through an all-pass network of a length equal to a length of the time-reversed temporal frame, the all-pass network being configurable with a single parameter alpha;
wherein for positive values of alpha, a first two stages of the all-pass network are configured as low-pass filters and the all-pass network warps frequency content to higher frequencies;
wherein for negative values of alpha, the first two stages of the all-pass network are configured as high-pass filters and the all-pass network warps the frequency content to lower frequencies;
collecting an output of the all-pass network sequentially after passing the frequency warped time-reversed frame;
and
performing overlap-and-add on the frequency warped time-reversed temporal frames to provide a frequency warped signal.

2. The method of claim 1 , wherein the audio signal comprises a full band signal.

3. The method of claim 1 , wherein the audio signal is a sub-band signal.

4. The method of claim 1 , wherein the frequency warping is configured with a warping parameter that is a function of gain provided in the sub-band.

5. The method of claim 1 , further comprising processing the audio signals to mitigate acoustic feedback in a system having a microphone and a speaker, wherein the frequency warped signal is provided in a forward path of the system.

6. The method of claim 5 , further comprising performing adaptive feedback cancellation (AFC) in the forward path using the frequency warped signal.

7. The method of claim 6 , wherein the AFC is a least mean square AFC process.

8. The method of claim 1 , further comprising performing dynamic range compression on the audio signal prior to performing frequency warping.

9. A hearing aid device, comprising:
a microphone configured to receive an audible input signal from an environment and convert the audible input signal to an electrical audio input signal;
a hearing aid processing circuit configured for processing the electrical audio input signal;
a frequency warping circuit configured to receive an electrical audio signal from the hearing aid processing circuit, the frequency warping circuit being configured to:
divide the electrical audio signal into overlapping frames;
window each temporal frame;
time-reverse the windowed temporal frames;
for each of the time-reversed windowed temporal frames, pass the time-reversed temporal frame through an all-pass network of a length equal to a length of the time-reversed temporal frame, the all-pass network being configurable with a single parameter alpha;
wherein for positive values of alpha, a first two stages of the all-pass network are configured as low-pass filters and the all-pass network warps frequency content to higher frequencies;
wherein for negative values of alpha, the first two stages of the all-pass network are configured as high-pass filters and the all-pass network warps the frequency content to lower frequencies;
collect an output of the all-pass network sequentially after passing the frequency warped time-reversed frame;
perform overlap-and-add on the frequency warped time-reversed temporal frames
to provide a frequency warped signal to the speaker;

a speaker configured to receive the frequency warped signal from the multi-band frequency warping circuit and emit an audible output signal into an ear of a user; and
an adaptive feedback cancellation circuit located in an acoustic feedback path between an output of the microphone and an input to the speaker, the adaptive feedback cancellation circuit being configured to receive as inputs a portion of the electrical audio input signal from the microphone and the electrical audio signal from the multi-band frequency warping circuit and provide an output as an input to the multi-band hearing aid processing circuit.

10. The hearing aid device of claim 9 , wherein the frequency warping circuit includes a chain of all-pass networks for performing the frequency warping.

11. The hearing aid device of claim 9 , wherein the frequency warping circuit performs frequency warping with a different warping parameter in at least two of sub-bands.

12. The hearing aid device of claim 9 , wherein the frequency warping circuit performs frequency warping with negative values of a warping parameter in each of the sub-bands.

13. The hearing aid device of claim 9 , wherein the frequency warping circuit performs frequency warping in each of the sub-bands with a warping parameter that is a function of gain provided in the respective sub-band.

14. The hearing aid device of claim 9 , wherein the frequency warping circuit performs frequency warping in at least one of the sub-bands with a warping parameter that is a function of one or more hearing aid parameters.

15. The hearing aid device of claim 9 , wherein the frequency warping circuit performs frequency warping in at least one of the sub-bands with a warping parameter that is a function of gain provided in the sub-band.

16. The hearing aid device of claim 9 , wherein the audio signal comprises a full band signal.

17. The hearing aid device of claim 9 , wherein the audio signal comprises a sub-band signal.

18. The hearing aid device of claim 9 , wherein the frequency warping is configured with a warping parameter that is a function of gain provided in the sub-band.

19. The hearing aid device of claim 9 , wherein the frequency warping circuit is further configured to perform adaptive feedback cancellation (AFC) in a forward path using the frequency warped signal.

20. The hearing aid device of claim 19 , wherein the AFC is a least mean square AFC process.

21. The hearing aid device of claim 9 , wherein the frequency warping circuit is further configured to performing dynamic range compression on the audio signal prior to performing frequency warping.

Assignees

• Univ California

Inventors

• Garudadri Harinath
• Lee Ching-Hua
• Chen Kuan-Lin
• Harris Fred
• Rao Bhaskar

Classifications

• H04R25/453 Primary

  electronically · CPC title

• H04R2460/01

  Hearing devices using active noise cancellation · CPC title