# US 10,375,486 B2 · Hearing device comprising a beamformer filtering unit

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- Number: US 10,375,486 B2
- Document ID: US10375486B2
- Status: Granted
- Kind: B2
- Application number: 16/194,082
- Filed: 2018-11-16
- Published: 2019-03-21
- Granted: 2019-08-06
- Earliest claimed: 2016-04-08
- Assignees: Oticon A/S
- Applicants: Oticon A/S
- Inventors: Andreas Thelander Bertelsen; Michael Syskind Pedersen; Jesper Jensen; Thomas Kaulberg; Morten Christophersen
- Web page: https://patentgrep.com/patent/US10375486B2

## CPC

- H04R 25/407: {Circuits for combining signals of a plurality of transducers}
- G10L 21/0232: Processing in the frequency domain
- H04R 25/353: {Frequency, e.g. frequency shift or compression}
- H04R 25/405: {by combining a plurality of transducers}
- H04R 25/558: {Remote control, e.g. of amplification, frequency}
- G10L 2021/02166: {Microphone arrays; Beamforming}
- H04R 25/552: {Binaural}
- H04R 25/554: {using a wireless connection, e.g. between microphone and amplifier or using Tcoils}
- H04R 25/606: {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}
- H04R 2225/41: Detection or adaptation of hearing aid parameters or programs to listening situation, e.g. pub, forest
- H04R 2225/43: Signal processing in hearing aids to enhance the speech intelligibility
- H04R 2225/61: Aspects relating to mechanical or electronic switches or control elements, e.g. functioning
- H04R 2430/20: Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic (H04R2203/12 takes precedence)
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING

## 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).

## Claims

### 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 for converting an input sound to first IN1 and second IN2 electric input signals, respectively,
an adaptive beamformer filter for providing a resulting beamformed signal YBF, 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 Wo1(k), Wo2(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 Wc1(k), Wc2(k) representing a second beam pattern (C),
an adaptive beamformer processor for providing an adaptively determined adaptation parameter βopt(k) representing an adaptive beam pattern,
said memory further comprising a fixed frequency dependent adaptation parameter βfix(k) representing a third, fixed beam pattern (OO),
a mixer configured to provide a resulting complex, frequency dependent adaptation parameter βmix(k) as a combination of said fixed frequency dependent adaptation parameter βfix(k) and said adaptively determined frequency dependent adaptation parameter βopt(k),
a resulting beamformer (Y) for providing said resulting beamformed signal YBF based on said first and second electric input signals IN1 and IN2, said first and second sets of complex frequency dependent weighting parameters Wo1(k), Wo2(k) and Wc1(k), Wc2(k), and said resulting complex, frequency dependent adaptation parameter βmix(k).

### Claim 2 (depends on 1)

A hearing aid according to claim 1 wherein said adaptively determined adaptation parameter βopt(k) and said fixed adaptation parameter βfix(k) are based on said first and second sets of complex frequency dependent weighting parameters Wo1(k), Wo2(k) and Wc1(k), Wc2(k), respectively.

### Claim 3 (depends on 1)

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

### Claim 4 (depends on 1)

A hearing aid according to claim 1 wherein said first and second sets of weighting parameters Wo1(k), Wo2(k) and Wc1(k), Wc2(k), respectively, are predetermined values.

### Claim 5 (depends on 1)

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

### Claim 6 (depends on 1)

A hearing aid according to claim 1 wherein said resulting beamformed signal YBF is determined according to the following expression:
YBF=IN1(k)·(Wo1(k)*−βmix(k)·Wc1(k)*)+IN2(k)·(Wo2(k)*−βmix(k)·Wc2(k)*),
where * denotes complex conjugation.

### Claim 7 (depends on 1)

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).

### Claim 8 (depends on 1)

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.

### Claim 9 (depends on 1)

A hearing aid according to claim 1 where the first and second sets of weighting parameters Wo1(k), Wo2(k) and Wc1(k), Wc2(k), respectively, are updated during operation of the hearing aid.

### Claim 10 (depends on 1)

A hearing aid according to claim 1 wherein the adaptive beamformer processor is configured to determine the adaptation parameter βopt(k) from the following expression
β
opt
=
〈
C
*
⁢
O
〉
〈

C

2
〉
,
where * denotes complex conjugation, and <·> denotes the statistical expectation operator.

### Claim 11 (depends on 1)

A hearing aid according to claim 1 wherein the adaptive beamformer processor is configured to determine the adaptation parameter βopt(k) from the following expression
β
opt
=
w
O
H
⁢
C
v
⁢
w
C
w
C
H
⁢
C
v
⁢
w
C
,
where wO and wC are the beamformer weights for the delay and sum O and the delay and subtract C beamformers, respectively, Cv is the noise covariance matrix, and H denotes Hermetian transposition.

### Claim 12 (depends on 1)

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.

### Claim 13 (depends on 1)

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.

### Claim 14 (depends on 1)

A hearing aid according to claim 1 wherein the resulting adaptation parameter βmix is determined as a weighted sum of the adaptation parameters βopt and βfix according to the expression
βmix=w1βopt+w2βfix
where w1 and w2 are complex or real weighting factors.

### Claim 15 (depends on 1)

A hearing aid according to claim 1 wherein the resulting adaptation parameter βmix is determined as a linear combination of the adaptation parameters βopt and βfix according to the expression
βmix=αβopt+(1−α)βfix,
where the weighting parameter α is a real number between 0 and 1.

### Claim 16 (depends on 15)

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.

### Claim 17 (depends on 1)

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

### Claim 18 (depends on 1)

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

### Claim 19

A method of constraining an adaptive beamformer for providing a resulting beamformed signal YBF of a hearing aid from first IN1 and second IN2 electric input signals, the method comprising
storing first and second complex frequency dependent weighting parameters Wo1(k), Wo2(k), and Wc1(k), Wc2(k), respectively, representing first and second beam patterns O and C, respectively, where k is a frequency index, k=1, 2, . . . , K,
adaptively determining an adaptation parameter βopt(k) representing an adaptive beam pattern,
storing a fixed frequency dependent adaptation parameter βfix(k) representing a third fixed beam pattern (OO),
providing a complex, frequency dependent adaptation parameter βmix(k) as a combination of said fixed frequency dependent adaptation parameter βfix(k) and said adaptively determined frequency dependent adaptation parameter βopt(k),
providing a resulting beamformer (Y) as a weighted combination of said first and second beam patterns O and C: Y(k)=O(k)−βmix(k)·C(k), where βmix(k) is said complex, frequency dependent adaptation parameter, and providing said resulting beamformed signal YBF from the first IN1 and second IN2 electric input signals.

### Claim 20 (depends on 19)

A non-transitory computer readable medium having stored there on a computer program comprising instructions which, when the program is executed by a computer, causes the computer to carry out the method of claim 19.