Hearing device comprising a beamformer filtering unit

Patent metadata

Field	Value
Publication number	US-2017295437-A1
Application number	US-201715482188-A
Country	US
Kind code	A1
Filing date	Apr 7, 2017
Priority date	Apr 8, 2016
Publication date	Oct 12, 2017
Grant date	—

Abstract

A hearing aid comprises a) first and second microphones b) an adaptive beamformer filtering unit comprising, b1) a first and second memories comprising a first and second sets of complex frequency dependent weighting parameters representing a first and second beam patterns, where said first and second sets of weighting parameters are predetermined initial values or values updated during operation of the hearing aid, b3) an adaptive beamformer processing unit providing an adaptation parameter β opt (k) representing an adaptive beam pattern configured to attenuate unwanted noise under the constraint that sound from a target direction is essentially unaltered, b4) a third memory comprising a fixed adaptation parameter β fix (k) representing a third, fixed beam pattern, b5) a mixing unit providing a resulting complex, frequency dependent adaptation parameter β mix (k) as a combination of said fixed and adaptively determined frequency dependent adaptation parameters β fix (k) and β opt (k), respectively, and b6) a resulting beamformer (Y) for providing a resulting beamformed signal Y BF 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 β mix (k).

First claim

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 (M 1 , M 2 ; M BTE1 , M BTE2 ) for converting an input sound to first IN 1 and second IN 2 electric input signals, respectively, an adaptive beamformer filtering unit (BFU) for providing a resulting beamformed signal Y BF , based on said first and second electric input signals, the adaptive beamformer filtering unit comprising, a first 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, a second memory comprising a second set of complex frequency dependent weighting parameters W c1 (k), W c2 (k) representing a second beam pattern (C),
where said first and second sets of weighting parameters W o1 (k), W o2 (k) and W c1 (k), W c2 (k), respectively, are predetermined initial values or values updated during operation of the hearing aid,
an adaptive beamformer processing unit for providing an adaptively determined adaptation parameter β opt (k) representing an adaptive beam pattern (OPT) configured to attenuate unwanted noise under the constraint that sound from a target direction is essentially unaltered, a third memory comprising a fixed adaptation parameter β fix (k) representing a third, fixed beam pattern (OO), a mixing unit 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 control unit 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 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.

5 . 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).

6 . 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.

7 . 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.

8 . A hearing aid according to claim 1 wherein the adaptive beamformer processing unit 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.

9 . A hearing aid according to claim 1 wherein the adaptive beamformer processing unit 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.

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

11 . 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.

12 . A hearing aid according to claim 1 wherein the resulting adaptation parameter β mix is determined as belonging to points on a circle in the complex plane, or an approximation thereof.

13 . A hearing aid according to claim 11 wherein the weighting parameter α is a function of a current acoustic environment and/or of a present cognitive load of the user.

14 . A hearing aid according to claim 1 comprising a hearing instrument, a headset, an earphone, an ear protection device or a combination thereof.

15 . A method of constraining an adaptive beamformer for providing a resulting beamformed signal Y BF of a hearing aid, the method comprising
Providing first and second complex frequency dependent weighting parameters W o1 (k), W o2 (k), and W c1 (k), W c2 (k), respectively, representing first and second beam patterns O and C, respectively, where k is a frequency index, k=1, 2, . . . , K, Providing an adaptively determined adaptation parameter β opt (k) representing an adaptive beam pattern (OPT) configured to attenuate unwanted noise un

Assignees

• Oticon As

Inventors

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

Classifications

• 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

• H04R2225/41

  Detection or adaptation of hearing aid parameters or programs to listening situation, e.g. pub, forest · CPC title

• H04R25/552

  Binaural · CPC title

• H04R25/353

  Frequency, e.g. frequency shift or compression · CPC title

• H04R25/558

  Remote control, e.g. of amplification, frequency · CPC title