Hearing device comprising a beamformer filtering unit

Patent metadata

Field	Value
Publication number	US-10375486-B2
Application number	US-201816194082-A
Country	US
Kind code	B2
Filing date	Nov 16, 2018
Priority date	Apr 8, 2016
Publication date	Aug 6, 2019
Grant date	Aug 6, 2019

Abstract

A hearing aid comprises a) first and second microphones b) an adaptive beamformer filtering unit comprising, b1) a memory comprising a first and second sets of complex frequency dependent weighting parameters representing a first and second beam patterns, b3) an adaptive beamformer processing unit providing an adaptation parameter βopt(k) representing an adaptive beam pattern, b4) a memory comprising a fixed adaptation parameter βfix(k) representing a third, fixed beam pattern, b5) a mixing unit providing a resulting complex, frequency dependent adaptation parameter βmix(k) as a combination of said fixed and adaptively determined frequency dependent adaptation parameters βfix(k) and βopt(k), respectively, and b6) a resulting beamformer (Y) for providing a resulting beamformed signal YBF based on first and second microphone signals, said first and second sets of complex frequency dependent weighting parameters, and said resulting complex, frequency dependent adaptation parameter βmix(k).

First claim

The invention claimed is:

1. A hearing aid adapted for being located in an operational position at or in or behind an ear or fully or partially implanted in the head of a user, the hearing aid comprising
first and second microphones for converting an input sound to first IN 1 and second IN 2 electric input signals, respectively,
an adaptive beamformer filter for providing a resulting beamformed signal Y BF , based on said first and second electric input signals, the adaptive beamformer filter comprising,
a memory comprising
a first set of complex frequency dependent weighting parameters W o1 (k), W o2 (k) representing a first beam pattern (O), where k is a frequency index, k=1, 2, . . . , K, and
a second set of complex frequency dependent weighting parameters W c1 (k), W c2 (k) representing a second beam pattern (C),

an adaptive beamformer processor for providing an adaptively determined adaptation parameter β opt (k) representing an adaptive beam pattern,
said memory further comprising a fixed frequency dependent adaptation parameter β fix (k) representing a third, fixed beam pattern (OO),
a mixer configured to provide a resulting complex, frequency dependent adaptation parameter β mix (k) as a combination of said fixed frequency dependent adaptation parameter β fix (k) and said adaptively determined frequency dependent adaptation parameter β opt (k),
a resulting beamformer (Y) for providing said resulting beamformed signal Y BF based on said first and second electric input signals IN 1 and IN 2 , said first and second sets of complex frequency dependent weighting parameters W o1 (k), W o2 (k) and W c1 (k), W c2 (k), and said resulting complex, frequency dependent adaptation parameter β mix (k).

2. A hearing aid according to claim 1 wherein said adaptively determined adaptation parameter β opt (k) and said fixed adaptation parameter β fix (k) are based on said first and second sets of complex frequency dependent weighting parameters W o1 (k), W o2 (k) and W c1 (k), W c2 (k), respectively.

3. A hearing aid according to claim 1 comprising a controller for dynamically controlling the relative weighting of the fixed and adaptively determined adaptation parameters β fix (k) and β opt (k), respectively.

4. A hearing aid according to claim 1 wherein said first and second sets of weighting parameters W o1 (k), W o2 (k) and W c1 (k), W c2 (k), respectively, are predetermined values.

5. A hearing aid according to claim 1 wherein said adaptive beamformer processor for providing said adaptively determined adaptation parameter β opt (k) representing said adaptive beam pattern is configured to attenuate unwanted noise under the constraint that sound from a target direction is essentially unaltered.

6. A hearing aid according to claim 1 wherein said resulting beamformed signal Y BF is determined according to the following expression:
Y BF =IN 1 ( k )·( W o1 ( k )*−β mix ( k )· W c1 ( k )*)+ IN 2 ( k )·( W o2 ( k )*−β mix ( k )· W c2 ( k )*),

where * denotes complex conjugation.

7. A hearing aid according to claim 1 wherein said first beam pattern (O) represents the beam pattern of a delay and sum beamformer and wherein said second beam pattern (C) represents a beam pattern of a delay and subtract beamformer (C).

8. A hearing aid according to claim 1 configured to provide that the direction to the target signal source relative to a predefined direction is configurable.

9. A hearing aid according to claim 1 where the first and second sets of weighting parameters W o1 (k), W o2 (k) and W c1 (k), W c2 (k), respectively, are updated during operation of the hearing aid.

10. A hearing aid according to claim 1 wherein the adaptive beamformer processor is configured to determine the adaptation parameter β opt (k) from the following expression

β
opt

=

〈

C
*

⁢
O

〉

〈


C


2

〉

,

where * denotes complex conjugation, and <·> denotes the statistical expectation operator.

11. A hearing aid according to claim 1 wherein the adaptive beamformer processor is configured to determine the adaptation parameter β opt (k) from the following expression

β
opt

=

w
O
H

⁢

C
v

⁢

w
C

w
C
H

⁢

C
v

⁢

w
C

,

where w O and w C are the beamformer weights for the delay and sum O and the delay and subtract C beamformers, respectively, C v is the noise covariance matrix, and H denotes Hermetian transposition.

12. A hearing aid according to claim 1 wherein the third, fixed beam pattern is configured to provide a fixed beam pattern having a desired directional shape suitable for listening to sounds from all directions.

13. A hearing aid according to claim 1 wherein the third fixed beamformer is configured to provide an omni-directional response, or a response, which, at least at relatively low frequencies, such as at all frequencies considered the hearing aid, mimics the directional response of a human ear.

14. A hearing aid according to claim 1 wherein the resulting adaptation parameter β mix is determined as a weighted sum of the adaptation parameters β opt and β fix according to the expression
β mix =w 1 β opt +w 2 β fix

where w 1 and w 2 are complex or real weighting factors.

15. A hearing aid according to claim 1 wherein the resulting adaptation parameter β mix is determined as a linear combination of the adaptation parameters β opt and β fix according to the expression
β mix =αβ opt +(1−α)β fix ,

where the weighting parameter α is a real number between 0 and 1.

16. A hearing aid according to claim 15 wherein the weighting parameter α is a function of a current acoustic environment and/or of a present cognitive load of the user.

17. A hearing aid according to claim 1 wherein the resulting adaptation parameter β mix is

Assignees

• Oticon As

Inventors

• Bertelsen Andreas Thelander
• Pedersen Michael Syskind
• Jensen Jesper
• Kaulberg Thomas
• Christophersen Morten

Classifications

• H04R2430/23

  Direction finding using a sum-delay beam-former · CPC title

• H04R2430/20

  Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic (H04R2203/12 takes precedence) · CPC title

• H04R2225/61

  Aspects relating to mechanical or electronic switches or control elements, e.g. functioning · CPC title

• H04R2225/43

  Signal processing in hearing aids to enhance the speech intelligibility · CPC title

• H04R25/606

  acting directly on the eardrum, the ossicles or the skull, e.g. mastoid, tooth, maxillary or mandibular bone, or mechanically stimulating the cochlea, e.g. at the oval window · CPC title