# US 12,003,673 B2 · Acoustic echo cancellation control for distributed audio devices

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- Number: US 12,003,673 B2
- Document ID: US12003673B2
- Status: Granted
- Kind: B2
- Application number: 17/628,732
- Filed: 2020-07-29
- Published: 2023-10-05
- Granted: 2024-06-04
- Earliest claimed: 2019-07-30
- Assignees: Dolby Laboratories Licensing Corporation; Dolby International AB
- Applicants: Dolby Laboratories Licensing Corporation; Dolby International AB
- Inventors: Glenn N. Dickins; Christopher Graham Hines; David Gunawan; Richard J. Cartwright; Alan J. Seefeldt; Daniel Arteaga; Mark R. P. Thomas; Joshua B. Lando
- Web page: https://patentgrep.com/patent/US12003673B2

## CPC

- H04M 9/082: {using echo cancellers (echo cancellers per se H04B3/23)}
- G01S 5/18: using ultrasonic, sonic or infrasonic waves
- G10L 15/22: Procedures used during a speech recognition process, e.g. man-machine dialogue
- G10L 21/0316: by changing the amplitude
- H04R 3/02: for preventing acoustic reaction {, i.e. acoustic oscillatory feedback (specially adapted for hearing aids H04R25/453)}
- G10L 21/034: Automatic adjustment
- G10L 2015/223: {Execution procedure of a spoken command}
- H04M 1/6033: {for providing handsfree use or a loudspeaker mode in telephone sets (arrangements for preventing acoustic echo H04M9/08)}
- H04R 3/005: {for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407)}
- H04R 3/12: for distributing signals to two or more loudspeakers {(specially adapted for hearing aids H04R25/407)}
- H04R 27/00: Public address systems (circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; {monitoring or testing arrangements for public address systems H04R29/007}; amplifiers H03F)
- H04R 2227/005: Audio distribution systems for home, i.e. multi-room use
- H04R 2227/007: Electronic adaptation of audio signals to reverberation of the listening space for PA
- H04R 2420/01: Input selection or mixing for amplifiers or loudspeakers
- H04R 2430/01: Aspects of volume control, not necessarily automatic, in sound systems
- H04R 2430/03: Synergistic effects of band splitting and sub-band processing
- H04S 7/303: {Tracking of listener position or orientation}
- H04S 7/305: {Electronic adaptation of stereophonic audio signals to reverberation of the listening space (H04S7/301 takes precedence)}
- H04S 2400/13: Aspects of volume control, not necessarily automatic, in stereophonic sound systems
- H04S 2420/07: Synergistic effects of band splitting and sub-band processing
- H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08)
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- 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)
- H04S: STEREOPHONIC SYSTEMS

## Abstract

An audio processing method may involve receiving output signals from each microphone of a plurality of microphones in an audio environment, the output signals corresponding to a current utterance of a person and determining, based on the output signals, one or more aspects of context information relating to the person, including an estimated current proximity of the person to one or more microphone locations. The method may involve selecting two or more loudspeaker-equipped audio devices based, at least in part, on the one or more aspects of the context information, determining one or more types of audio processing changes to apply to audio data being rendered to loudspeaker feed signals for the audio devices and causing one or more types of audio processing changes to be applied. In some examples, the audio processing changes have the effect of increasing a speech to echo ratio at one or more microphones.

## Claims

### Claim 1

An audio session management method, comprising:
receiving output signals from each microphone of a plurality of microphones in an audio environment, each microphone of the plurality of microphones residing in a microphone location of the audio environment, the output signals including signals corresponding to a current utterance of a person;
determining, based on the output signals, one or more aspects of context information relating to the person, the context information including at least one of an estimated current location of the person or an estimated current proximity of the person to one or more microphone locations;
determining a closest loudspeaker-equipped audio device that is closest to the microphone location closest to the estimated current location of the person;
selecting two or more audio devices of the audio environment based, at least in part, on the one or more aspects of the context information, the two or more audio devices each including at least one loudspeaker and wherein the two or more audio devices include the closest loudspeaker-equipped audio device;
determining one or more types of audio processing changes to apply to audio data being rendered to loudspeaker feed signals for the two or more audio devices, the audio processing changes having an effect of increasing a speech to echo ratio at the microphone closest to the estimated current location of the person, wherein the echo comprises at least some of audio outputted by the two or more audio devices, and wherein at least one of the audio processing changes for the closest audio device is different from an audio processing change for a second audio device of said at least two audio devices, and wherein the one or more types of audio processing changes cause a reduction in loudspeaker reproduction level for the closest audio device; and
causing the one or more types of audio processing changes to be applied.

### Claim 2 (depends on 1)

The method of claim 1, wherein the one or more types of audio processing changes involve spectral modification.

### Claim 3 (depends on 2)

The method of claim 2, wherein the spectral modification involves reducing a level of audio data in a frequency band between 500 Hz and 3 KHz.

### Claim 4 (depends on 1)

The method of any one of the claim 1, wherein the one or more types of audio processing changes cause a reduction in loudspeaker reproduction level for the loudspeakers of the two or more audio devices.

### Claim 5 (depends on 1)

The method of claim 1, wherein selecting two or more audio devices of the audio environment comprises selecting N loudspeaker-equipped audio devices of the audio environment, N being an integer greater than 2.

### Claim 6 (depends on 1)

The method of claim 1, wherein selecting the two or more audio devices of the audio environment is based, at least in part, on an estimated current location of the person relative to at least one of a microphone location or a loudspeaker-equipped audio device location.

### Claim 7 (depends on 1)

The method of claim 1, wherein the one or more types of audio processing changes involve changing a rendering process to warp a rendering of audio signals away from the estimated current location of the person.

### Claim 8 (depends on 1)

The method of claim 1, wherein the one or more types of audio processing changes involve inserting at least one gap into at least one selected frequency band of an audio playback signal.

### Claim 9 (depends on 1)

The method of claim 1, wherein the one or more types of audio processing changes involve dynamic range compression.

### Claim 10 (depends on 1)

The method of claim 1, wherein selecting the two or more audio devices is based, at least in part, on a signal-to-echo ratio estimation for one or more microphone locations.

### Claim 11 (depends on 10)

The method of claim 10, wherein selecting the two or more audio devices is based, at least in part, on determining whether the signal-to-echo ratio estimation is less than or equal to a signal-to-echo ratio threshold.

### Claim 12 (depends on 10)

The method of claim 10, wherein determining the one or more types of audio processing changes is based on an optimization of a cost function that is based, at least in part, on the signal-to-echo ratio estimation.

### Claim 13 (depends on 12)

The method of claim 12, wherein the cost function is based, at least in part, on rendering performance.

### Claim 14 (depends on 1)

The method of claim 1, wherein selecting the two or more audio devices is based, at least in part, on a proximity estimation.

### Claim 15 (depends on 1)

The method of claim 1, further comprising:
determining multiple current acoustic features from the output signals of each microphone;
applying a classifier to the multiple current acoustic features, wherein applying the classifier involves applying a model trained on previously-determined acoustic features derived from a plurality of previous utterances made by the person in a plurality of user zones in the environment; and
wherein determining one or more aspects of context information relating to the person involves determining, based at least in part on output from the classifier, an estimate of a user zone in which the person is currently located.

### Claim 16 (depends on 15)

The method of claim 15, wherein the estimate of the user zone is determined without reference to geometric locations of the plurality of microphones.

### Claim 17 (depends on 15)

The method of claim 15, wherein the current utterance and the previous utterances comprise wakeword utterances.

### Claim 18 (depends on 1)

The method of claim 1, further comprising selecting at least one microphone according to the one or more aspects of the context information.

### Claim 19 (depends on 1)

The method of claim 1, wherein the one or more microphones reside in multiple audio devices of the audio environment.

### Claim 20 (depends on 1)

The method of claim 1, wherein the one or more microphones reside in a single audio device of the audio environment.

### Claim 21 (depends on 1)

The method of claim 1, wherein at least one of the one or more microphone locations corresponds to multiple microphones of a single audio device.

### Claim 22 (depends on 1)

An apparatus configured to perform the method of claim 1.

### Claim 23 (depends on 1)

A system configured to perform the method of claim 1.

### Claim 24 (depends on 1)

One or more non-transitory media having software stored thereon, the software including instructions for controlling one or more devices to perform the method of claim 1.