# US 10,771,896 B2 · Crosstalk cancellation for speaker-based spatial rendering

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- Number: US 10,771,896 B2
- Document ID: US10771896B2
- Status: Granted
- Kind: B2
- Application number: 16/471,893
- Filed: 2017-04-14
- Published: 2020-01-23
- Granted: 2020-09-08
- Earliest claimed: 2017-04-14
- Assignees: Hewlett-Packard Development Company, L.P.
- Applicants: Hewlett-Packard Development Company, L.P.
- Inventors: Sunil Bharitkar
- Web page: https://patentgrep.com/patent/US10771896B2

## CPC

- H04R 3/14: Cross-over networks
- H04S 1/002: {Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution (control circuits for electronic adaptation of the sound field H04S7/30)}
- H04S 7/303: {Tracking of listener position or orientation}
- H04R 3/12: for distributing signals to two or more loudspeakers {(specially adapted for hearing aids H04R25/407)}
- H04S 2420/01: Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD]
- 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

In some examples, crosstalk cancellation for speaker-based spatial rendering may include perceptually smoothing head-related transfer functions (HRTFs) corresponding to ipsilateral and contralateral transfer paths of sound emitted from first and second speakers to corresponding first and second destinations. The crosstalk cancellation may further include inserting an inter-aural time difference in the perceptually smoothed HRTFs corresponding to the contralateral transfer paths. A crosstalk canceller may be generated by inverting the perceptually smoothed HRTFs corresponding to the ipsilateral transfer paths and the perceptually smoothed HRTFs corresponding to the contralateral transfer paths including the inserted inter-aural time difference.

## Claims

### Claim 1

An apparatus comprising:
a processor; and
a non-transitory computer readable medium storing machine readable instructions that when executed by the processor cause the processor to:
perceptually smooth head-related transfer functions (HRTFs) corresponding to ipsilateral and contralateral transfer paths of sound emitted from first and second speakers to corresponding first and second destinations;
insert an inter-aural time difference in the perceptually smoothed HRTFs corresponding to the contralateral transfer paths; and
generate a crosstalk canceller by inverting the perceptually smoothed HRTFs corresponding to the ipsilateral transfer paths and the perceptually smoothed HRTFs corresponding to the contralateral transfer paths including the inserted inter-aural time difference.

### Claim 2 (depends on 1)

The apparatus according to claim 1, wherein the perceptual smoothing includes phase and magnitude smoothing, or complex smoothing of the HRTFs.

### Claim 3 (depends on 1)

The apparatus according to claim 1, wherein
the first and second destinations correspond to first and second ears of a user, and
the inter-aural time difference is determined as a function of a head radius of the user, and an angle of one of the speakers from a median plane of a device that includes the speakers.

### Claim 4 (depends on 1)

The apparatus according to claim 1, wherein the instructions are further to cause the processor to:
determine a regularized matrix from the perceptually smoothed HRTFs corresponding to the ipsilateral transfer paths and the perceptually smoothed HRTFs corresponding to the contralateral transfer paths including the inserted inter-aural time difference; and
generate the crosstalk canceller by performing a time-domain inversion of the determined regularized matrix.

### Claim 5 (depends on 4)

The apparatus according to claim 4, wherein the instructions are further to cause the processor to:
determine a time-domain matrix from the perceptually smoothed HRTFs corresponding to the ipsilateral transfer paths and the perceptually smoothed HRTFs corresponding to the contralateral transfer paths including the inserted inter-aural time difference,
determine a regularization term to control inversion of the time-domain matrix, and
invert the time-domain matrix based on the regularization term to generate the regularized matrix.

### Claim 6 (depends on 5)

The apparatus according to claim 5, wherein the instructions are further to cause the processor to:
determine the regularization term to control the inversion of the time-domain matrix by comparing a condition number associated with a transpose of the time-domain matrix to a threshold; and
in response to a determination that the condition number is below the threshold, invert the time-domain matrix based on the regularization term to generate the regularized matrix.

### Claim 7 (depends on 4)

The apparatus according to claim 4, wherein the instructions are further to cause the processor to:
validate a condition number of the regularized matrix prior to the performing of the time-domain inversion of the regularized matrix.

### Claim 8 (depends on 1)

The apparatus according to claim 1, wherein the instructions are further to cause the processor to:
attenuate a contralateral response of the first and second speakers based on application of the crosstalk canceller to signals received by the first and second speakers.

### Claim 9

A method comprising:
perceptually smoothing, by a processor, head-related transfer functions (HRTFs) corresponding to ipsilateral and contralateral transfer paths of sound emitted from first and second speakers to corresponding first and second destinations;
inserting an inter-aural time difference in the perceptually smoothed HRTFs corresponding to the contralateral transfer paths;
determining a regularized matrix determined from the perceptually smoothed HRTFs corresponding to the ipsilateral transfer paths and the perceptually smoothed HRTFs corresponding to the contralateral transfer paths including the inserted inter-aural time difference; and
generating a crosstalk canceller by performing a time-domain inversion of the determined regularized matrix.

### Claim 10 (depends on 9)

The method according to claim 9, wherein the first and second destinations correspond to first and second ears of a user, further comprising:
determining the inter-aural time difference as a function of a head radius of the user, and an angle of one of the speakers from a median plane of a device that includes the speakers.

### Claim 11 (depends on 9)

The method according to claim 9, further comprising:
validating a condition number of the regularized matrix prior to the performing of the time-domain inversion of the regularized matrix.

### Claim 12 (depends on 9)

The method according to claim 9, further comprising:
attenuating a contralateral response of the first and second speakers based on application of the crosstalk canceller to signals received by the first and second speakers.

### Claim 13

A non-transitory computer readable medium having stored thereon machine readable instructions, the machine readable instructions, when executed, cause a processor to:
perceptually smooth head-related transfer functions (HRTFs) corresponding to ipsilateral and contralateral transfer paths of sound emitted from first and second speakers to corresponding first and second destinations;
insert an inter-aural time difference in the perceptually smoothed HRTFs corresponding to the contralateral transfer paths;
determine a time-domain matrix from the perceptually smoothed HRTFs corresponding to the ipsilateral transfer paths and the perceptually smoothed HRTFs corresponding to the contralateral transfer paths including the inserted inter-aural time difference;
determine a regularization term to control inversion of the time-domain matrix;
invert the time-domain matrix based on the regularization term to generate a regularized matrix; and
generate a crosstalk canceller by performing a time-domain inversion of the regularized matrix.

### Claim 14 (depends on 13)

The non-transitory computer readable medium according to claim 13, wherein the instructions are further to cause the processor to:
determine the regularization term to control the inversion of the time-domain matrix by comparing a condition number associated with a transpose of the time-domain matrix to a threshold; and
in response to a determination that the condition number is below the threshold, invert the time-domain matrix based on the regularization term to generate the regularized matrix.

### Claim 15 (depends on 13)

The non-transitory computer readable medium according to claim 13, wherein the instructions are further to cause the processor to:
attenuate a contralateral response of the first and second speakers based on application of the crosstalk canceller to signals received by the first and second speakers.