# US 10,482,894 B2 · Dereverberation device and hearing aid

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- Number: US 10,482,894 B2
- Document ID: US10482894B2
- Status: Granted
- Kind: B2
- Application number: 16/279,486
- Filed: 2019-02-19
- Published: 2019-08-29
- Granted: 2019-11-19
- Earliest claimed: 2018-02-23
- Assignees: Rion Co., Ltd.
- Applicants: RION Co., Ltd.
- Inventors: Masatoshi Osawa; Masahiro Sunohara; Yoichi Fujisaka; Yoko Fujishima
- Web page: https://patentgrep.com/patent/US10482894B2

## CPC

- G10L 21/0208: Noise filtering
- G10K 15/08: Arrangements for producing a reverberation or echo sound {(modifying acoustic properties to change reverberation time G10K11/002)}
- G10L 21/034: Automatic adjustment
- G10L 21/0324: Details of processing therefor
- G10L 2021/02082: {the noise being echo, reverberation of the speech}
- H04R 1/1083: {Reduction of ambient noise (active noise reduction per se G10K11/175; protective devices for the ear, e.g. providing acoustic protection A61F11/06)}
- H04R 25/505: {using digital signal processing}
- H04R 2225/43: Signal processing in hearing aids to enhance the speech intelligibility
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- 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)

## Abstract

A dereverberation device includes an input instantaneous value calculation unit configured to calculate an input instantaneous value based on an input signal; a reverberation estimation unit configured to calculate a moving average of the input instantaneous value as a reverberation component; a gain calculation unit configured to calculate, with the input instantaneous value and the reverberation component, a first gain as a basic gain for the input signal; a gain suppression control unit configured to calculate, according to a ratio between the input instantaneous value and the reverberation component, a second gain changing within a range between a predetermined lower limit and a predetermined upper limit, thereby outputting a larger one of the first gain or the second gain as a third gain; and a gain processing unit configured to multiply the input signal by the third gain.

## Claims

### Claim 1

A dereverberation device comprising:
an input instantaneous value calculation unit configured to calculate an input instantaneous value based on an input signal;
a reverberation estimation unit configured to calculate a moving average of the input instantaneous value as a reverberation component;
a gain calculation unit configured to calculate, with the input instantaneous value and the reverberation component, a first gain as a basic gain for the input signal;
a gain suppression control unit configured to calculate, according to a ratio between the input instantaneous value and the reverberation component, a second gain changing within a range between a predetermined lower limit and a predetermined upper limit, thereby outputting a larger one of the first gain or the second gain as a third gain; and
a gain processing unit configured to multiply the input signal by the third gain.

### Claim 2 (depends on 1)

The dereverberation device according to claim 1, wherein
the input instantaneous value is calculated based on an envelope of a value correlating with an absolute value or a square of the input signal, and
the reverberation component is calculated according to an index moving average of the input instantaneous value.

### Claim 3 (depends on 1)

The dereverberation device according to claim 1, wherein
the gain suppression control unit
gradually decreases the second gain toward the lower limit in a case where the input instantaneous value is smaller than the reverberation component, and
increases the second gain toward the upper limit in other cases than the case where the input instantaneous value is smaller than the reverberation component.

### Claim 4 (depends on 1)

The dereverberation device according to claim 1, further comprising:
a smoothing unit configured to perform smoothing by smoothing processing for the third gain.

### Claim 5 (depends on 1)

The dereverberation device according to claim 1, further comprising:
an analysis filter bank configured to divide an external input signal into multiple input signals as multiple frequency band components; and
a composite filter bank configured to synthesize the multiple frequency band components output from the gain processing unit to generate an output signal,
wherein each of the multiple frequency bands corresponds to one of the input instantaneous value calculation units, one of the reverberation estimation units, one of the gain calculation units, and one of the gain suppression control units.

### Claim 6 (depends on 5)

The dereverberation device according to claim 5, wherein
the lower limit and the upper limit are set separately for each of the multiple frequency bands.

### Claim 7

A hearing aid comprising:
a microphone configured to convert sound into an electric signal;
a receiver configured to convert an electric signal into sound;
an input instantaneous value calculation unit configured to calculate an input instantaneous value based on an input signal extracted from an output signal from the microphone;
a reverberation estimation unit configured to calculate a moving average of the input instantaneous value as a reverberation component;
a gain calculation unit configured to calculate, with the input instantaneous value and the reverberation component, a first gain as a basic gain for the input signal;
a gain suppression control unit configured to calculate, according to a ratio between the input instantaneous value and the reverberation component, a second gain changing within a range between a predetermined lower limit and a predetermined upper limit, thereby outputting a larger one of the first gain or the second gain as a third gain; and
a hearing aid processing unit configured to perform hearing aid processing according to a user for the input signal and including a gain processing unit configured to multiply the input signal by the third gain.