Feedback estimation based on deterministic sequences

Patent metadata

Field	Value
Publication number	US-9973863-B2
Application number	US-201514872925-A
Country	US
Kind code	B2
Filing date	Oct 1, 2015
Priority date	Oct 2, 2014
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

A hearing system comprises respective input and output transducers operationally coupled via a forward path comprising a configurable output combination unit having first and second signal inputs and a signal output. The first and second signal inputs are a signal of the forward path, and an output probe signal, respectively, and the output signal is electrically connected to the output transducer and configurable to consist of either of the first or second signal inputs, or a mixture thereof. The hearing system further comprises a configurable probe signal generator for generating the output probe signal, an adaptive feedback estimation unit for generating an estimate of an unintended feedback path, and a control unit for generating a control signal for controlling the output probe signal, which may comprise a perfect or almost perfect sequence and/or an almost perfect sweep sequence.

First claim

The invention claimed is:

1. A hearing system comprising
a hearing device comprising
an input transducer for converting an input sound from the environment of the hearing device to an electric input signal,
an output transducer for converting an electric output signal to an output sound, the input transducer, in a first mode of operation, being operationally coupled to the output transducer via a forward path, and
a configurable output combination unit in said forward path, said output combination unit having first and second signal inputs and a signal output, the first signal input being a signal of the forward path and the second signal input being an output probe signal, and the output signal being electrically connected to said output transducer and configurable to consist of either of the first or second signal inputs, or a mixture of the first and second signal inputs;
a configurable probe signal generator for generating said output probe signal,
an adaptive feedback estimation unit for generating an estimate of an unintended feedback path comprising an external feedback path from said output transducer to said input transducer, said feedback estimation unit comprising a feedback estimation filter using an adaptive feedback estimation algorithm, the adaptive feedback estimation unit being operationally coupled to the forward path,
a control unit for generating a control signal for controlling said configurable probe signal generator based on one or more control input signals, and

a detection unit operationally coupled to the forward path and providing one or more of said control unit signals, wherein
the control unit is configured to choose an appropriate probe signal based on properties of one or more current signals of the forward path, and
said configurable probe signal generator is adapted to generate or select said output probe signal from a multitude of different probe signals, wherein said multitude of different probe signals comprises a perfect or almost perfect sequence and/or a an almost perfect sweep sequence.

2. The hearing system according to claim 1 wherein almost perfect sequence (aPS) is a sequence of length N, whose elements k=0, 1, . . . , N−1, fulfill the criterion |r xx (0) aPS |/|Σ k≠0 r xx (k) aPS |≥10.

3. The hearing system according to claim 1 wherein said control unit is configured to initiate the generation of said output probe signal based on an initiation control input signal.

4. The hearing system according to claim 3 comprising a user interface from which said initiation control input signal can be generated.

5. The hearing system according to claim 3 comprising a programming interface to a programming device from which said initiation control input signal can be generated.

6. The hearing system according to claim 1 comprising a detection unit operationally coupled to the forward path and providing one or more of said control input signals.

7. The hearing system according to claim 6 wherein said detection unit comprises a noise estimation unit providing a noise estimation signal indicative of an estimate of a current noise level or a signal to noise ratio of a signal of the forward path originating from said electric input signal.

8. The hearing system according to claim 7 wherein the control unit is configured to select said perfect or almost perfect sequence or a perfect or almost perfect sweep as said output probe signal when said estimate of a current noise level or a signal to noise ratio is below a threshold noise level or a threshold signal to noise ratio, respectively.

9. The hearing system according to claim 1 wherein the adaptive feedback estimation algorithm is an LMS, NLMS, RLS or other adaptive algorithm.

10. The hearing system according to claim 1 wherein the feedback estimation filter has a length of L samples, and wherein L is larger than or equal to 32, such as larger than or equal to 48, such as larger than or equal to 64, such as larger than or equal to 128.

11. The hearing system according to claim 10 wherein the length L in samples of the feedback estimation filter is equal to the length N of the perfect or almost-perfect sequence.

12. The hearing system according to claim 1 wherein said multitude of different probe signals comprise a Golay sequence or one or more pure tones.

13. The hearing system according to claim 1 wherein said control unit is configured to choose an appropriate probe signal based on properties of one or more current signals of the forward path.

14. The hearing system according to claim 1 wherein said a configurable probe signal generator, said adaptive feedback estimation unit, and said control unit form part of the hearing device.

15. The hearing system according to claim 1 comprising a hearing aid or being constituted by a hearing aid.

16. A method of estimating a feedback path from an output transducer to an input transducer of a hearing device, the input transducer being configured for converting an input sound from the environment of the hearing device to an electric input signal, and the output transducer being configured for converting an electric output signal to an output sound, wherein the input transducer is operationally coupled to the output transducer via a forward path, the method comprising
generating an output probe signal,
providing that said electric output signal is formed as a weighted combination of said output probe signal and a signal of the forward path, and
generating an estimate of an unintended feedback path comprising an external feedback path from said output transducer to said input transducer by means of a feedback estimation filter using an adaptive feedback estimation algorithm, where the adaptive feedback estimation unit is operationally coupled to the forward path, and
generating a control output signal for controlling the generation of said output probe signal based on one or more control input signals provided from a detection unit operationally coupled to the forward path, and
generating or selecting said output probe signal from a multitude of different probe signals, wherein said multitude of different probe signals comprises a perfect or almost perfect sequence and/or an almost perfect sweep sequence, and
choosing an appropriate probe signal based on properties of one or more current signals of the forward path.

17. A data processing system comprising a processor and program code means for causing the processor to perform the steps of the method of claim 16 .

18. A hearing system according to claim 1 wherein the control unit is configured to choose an appropriate probe signal based on properties of one or more current signals of the forward path, e.g. its or their spectra, modulation, levels, auto-correlation, cross-correlation, etc.

19. A hearing system according to claim 4 comprising first and second hearing devices and an auxiliary device comprising said user interface for the hearing system, wherein the user interface is implemented as an APP in the auxiliary device.

20. A hearing system according to claim 1 comprising an interface to a remote control device.

21. A hearing system according to claim 20 wherein the remote control device comprises a telephone.

22. A hearing system according to claim 20 further configured to allow one or more control input signals to be generated via said interface to the remote control.

Assignees

• Oticon As

Inventors

• Guo Meng

Classifications

• H04R25/505

  using digital signal processing · CPC title

• H04R2460/15

  Determination of the acoustic seal of ear moulds or ear tips of hearing devices · CPC title

• H04R25/453 Primary

  electronically · CPC title

• H04R25/45

  Prevention of acoustic reaction, i.e. acoustic oscillatory feedback · CPC title

• H04R25/30

  Monitoring or testing of hearing aids, e.g. functioning, settings, battery power · CPC title