# US 10,771,914 B2 · Generating binaural audio in response to multi-channel audio using at least one feedback delay network

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- Number: US 10,771,914 B2
- Document ID: US10771914B2
- Status: Granted
- Kind: B2
- Application number: 16/777,599
- Filed: 2020-01-30
- Published: 2020-07-30
- Granted: 2020-09-08
- Earliest claimed: 2014-01-03
- Assignees: Dolby Laboratories Licensing Corporation
- Applicants: Dolby Laboratories Licensing Corporation
- Inventors: Kuan-Chieh Yen; Dirk Jeroen Breebaart; Grant A. Davidson; Rhonda Wilson; David M. Cooper; Zhiwei Shuang
- Web page: https://patentgrep.com/patent/US10771914B2

## CPC

- H04S 7/306: {For headphones}
- G10K 15/12: using electronic time-delay networks
- G10L 19/008: Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
- H04S 3/004: {For headphones}
- H04S 7/30: {Control circuits for electronic adaptation of the sound field}
- H04S 7/307: {Frequency adjustment, e.g. tone control (H04S7/301 takes precedence)}
- H04S 2400/01: Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved
- H04S 2400/03: Aspects of down-mixing multi-channel audio to configurations with lower numbers of playback channels, e.g. 7.1 -> 5.1 (H04S2400/01 takes precedence)
- H04S 2400/13: Aspects of volume control, not necessarily automatic, in stereophonic sound systems
- 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]
- H04S: STEREOPHONIC SYSTEMS
- 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
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING

## Abstract

In some embodiments, virtualization methods for generating a binaural signal in response to channels of a multi-channel audio signal, which apply a binaural room impulse response (BRIR) to each channel including by using at least one feedback delay network (FDN) to apply a common late reverberation to a downmix of the channels. In some embodiments, input signal channels are processed in a first processing path to apply to each channel a direct response and early reflection portion of a single-channel BRIR for the channel, and the downmix of the channels is processed in a second processing path including at least one FDN which applies the common late reverberation. Typically, the common late reverberation emulates collective macro attributes of late reverberation portions of at least some of the single-channel BRIRs. Other aspects are headphone virtualizers configured to perform any embodiment of the method.

## Claims

### Claim 1

A method for generating a binaural signal in response to a set of channels of a multi-channel audio input signal, the method comprising:
applying a binaural room impulse response, BRIR, to each channel of the set, thereby generating filtered signals; and
combining the filtered signals to generate the binaural signal,
wherein applying the BRIR to each channel of the set comprises using a late reverberation generator to introduce, in response to control values asserted to the late reverberation generator, a common late reverberation into a downmix of the channels of the set, wherein the common late reverberation emulates collective macro attributes of late reverberation portions of single-channel BRIRs shared across at least some channels of the set, and
wherein left-side channels of the multi-channel audio input signal are panned to a left channel of the downmix, and wherein right-side channels of the multi-channel audio input signal are panned to a right channel of the downmix.

### Claim 2 (depends on 1)

The method of claim 1, wherein applying a BRIR to each channel of the set comprises applying to each channel of the set a direct response and early reflection portion of the single-channel BRIR for the channel.

### Claim 3 (depends on 1)

The method of claim 1, wherein the late reverberation generator comprises a bank of feedback delay networks to apply the common late reverberation to the downmix, with each feedback delay network of the bank applying late reverberation to a different frequency band of the downmix.

### Claim 4 (depends on 3)

The method of claim 3, wherein each of the feedback delay networks is implemented in the complex quadrature mirror filter domain.

### Claim 5 (depends on 1)

The method of claim 1, wherein the late reverberation generator comprises a single feedback delay network to apply the common late reverberation to the downmix of the channels of the set, wherein the feedback delay network is implemented in the time domain.

### Claim 6

A system for generating a binaural signal in response to a set of channels of a multi-channel audio input signal, the system comprising one or more processors that:
apply a binaural room impulse response, BRIR, to each channel of the set, thereby generating filtered signals; and
combine the filtered signals to generate the binaural signal,
wherein applying the BRIR to each channel of the set comprises using a late reverberation generator to introduce, in response to control values asserted to the late reverberation generator, a common late reverberation into a downmix of the channels of the set, wherein the common late reverberation emulates collective macro attributes of late reverberation portions of single-channel BRIRs shared across at least some channels of the set, and
wherein left-side channels of the multi-channel audio input signal are panned to a left channel of the downmix, and wherein right-side channels of the multi-channel audio input signal are panned to a right channel of the downmix.

### Claim 7 (depends on 6)

The system of claim 6, wherein applying a BRIR to each channel of the set comprises applying to each channel of the set a direct response and early reflection portion of the single-channel BRIR for the channel.

### Claim 8 (depends on 6)

The system of claim 6, wherein the late reverberation generator includes a bank of feedback delay networks configured to apply the common late reverberation to the downmix, with each feedback delay network of the bank applying late reverberation to a different frequency band of the downmix.

### Claim 9 (depends on 8)

The system of claim 8, wherein each of the feedback delay networks is implemented in the complex quadrature mirror filter domain.

### Claim 10 (depends on 6)

The system of claim 6, wherein the late reverberation generator includes a feedback delay network implemented in the time domain, and the late reverberation generator is configured to process the downmix in the time domain in said feedback delay network to apply the common late reverberation to said downmix.

### Claim 11 (depends on 1)

A non-transitory computer readable storage medium comprising a sequence of instructions, wherein, when an audio signal processing device executes the sequence of instructions, the audio signal processing device performs the method of claim 1.