Method for feedback cancelling in hearing devices and hearing device with a feedback canceller

Patent metadata

Field	Value
Publication number	US-9578426-B2
Application number	US-201514663781-A
Country	US
Kind code	B2
Filing date	Mar 20, 2015
Priority date	Mar 20, 2015
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

An analysis filter bank decomposes a microphone signal into sub-band signals, a gain unit applies a frequency-dependent gain to the sub-band signals, and a synthesis filter bank converts the amplified sub-band signals into a signal, which is then output by a receiver. A first adaptive filter of a feedback canceller provides feedback compensation signals adapted to compensate acoustic feedback from the receiver to the microphone, whereby the feedback compensation signals are subtracted from corresponding signals from the sub-band signals. A second adaptive filter of the feedback canceller estimates cross-frequency signal components resulting from aliasing of signal components from one sub-band into one or more neighboring sub-bands caused by non-ideal sub-band signal decomposition in the analysis filter bank with overlapping sub-bands. Thereby, the first adaptive filter is adapted in dependence of the estimated cross-frequency signal components.

First claim

The invention claimed is:

1. A method for feedback cancelling in a hearing device comprising at least one microphone, an analysis filter bank, a gain unit, a synthesis filter bank, a receiver and a feedback canceller comprising a first adaptive filter and a cross filter, the method comprising:
the at least one microphone providing at least one microphone signal;
the analysis filter bank decomposing the at least one microphone signal into a first plurality of sub-band signals;
the gain unit applying a frequency-dependent gain to the first plurality of sub-band signals and providing a first plurality of amplified sub-band signals;
the synthesis filter bank converting the first plurality of amplified sub-band signals into a receiver input signal; and
the receiver outputting a sound signal dependent on the receiver input signal,

characterised in
the first adaptive filter providing a second plurality of feedback compensation signals adapted to compensate acoustic feedback from the receiver to the at least one microphone, and subtracting the second plurality of feedback compensation signals from corresponding signals from the first plurality of sub-band signals to provide a first plurality of feedback compensated sub-band signals;
the cross filter estimating a third plurality of cross-frequency signal components resulting from aliasing of signal components from one sub-band into one or more neighbouring sub-bands caused by non-ideal sub-band signal decomposition in the analysis filter bank with overlapping sub-bands; and
adapting the first adaptive filter in dependence of a difference between the first plurality of feedback compensated sub-band signals and corresponding components from the third plurality of estimated cross-frequency signal components.

2. The method of claim 1 , further comprising adapting the cross filter in dependence of the difference between the first plurality of feedback compensated sub-band signals and corresponding components from the third plurality of estimated cross-frequency signal components.

3. The method of claim 1 , further comprising adapting the first adaptive filter and the cross filter in dependence of the first plurality of amplified sub-band signals, or decomposing the receiver input signal into a fourth plurality of sub-band feedback signals and adapting the first adaptive filter and the cross filter in dependence of the fourth plurality of sub-band feedback signals.

4. The method of claim 1 , wherein the first plurality is larger than the second plurality and/or the second plurality is larger than or equal to the third plurality.

5. The method of claim 1 , wherein the first adaptive filter is an adaptive two partitions frequency domain filter, whose coefficients are updated according to the following normalised least-mean-squares equations:

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Assignees

• Phonak Ag
• Sonova Ag

Inventors

• Gigandet Xavier

Classifications

• H04R2460/01

  Hearing devices using active noise cancellation · CPC title

• H04R25/453 Primary

  electronically · CPC title