# US 10,313,814 B2 · Apparatus and method for sound stage enhancement

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- Number: US 10,313,814 B2
- Document ID: US10313814B2
- Status: Granted
- Kind: B2
- Application number: 15/965,446
- Filed: 2018-04-27
- Published: 2018-08-30
- Granted: 2019-06-04
- Earliest claimed: 2015-10-27
- Assignees: Ambidio, Inc.
- Applicants: Ambidio, Inc.
- Inventors: Tsai-Yi Wu; Pei-Lun Hsieh
- Web page: https://patentgrep.com/patent/US10313814B2

## CPC

- H04S 3/02: of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other
- G10K 11/175: using interference effects; Masking sound
- H03G 5/165: {Equalizers; Volume or gain control in limited frequency bands}
- H04R 5/04: Circuit arrangements, {e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments (combinations of amplifiers H03F3/68; stereophonic systems H04S)}
- H04S 1/007: {in which the audio signals are in digital form (data reduction aspects thereof based on psychoacoustics G10L19/02)}
- H04S 5/005: {of the pseudo five- or more-channel type, e.g. virtual surround}
- H04S 7/307: {Frequency adjustment, e.g. tone control (H04S7/301 takes precedence)}
- G10K 2210/3218: Filters other than the algorithm-related filters
- 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 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
- H03G: CONTROL OF AMPLIFICATION
- 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 method for processing an audio signal is performed at a computing device. The method includes the following steps: receiving a digital stereo audio input signal; extracting localization cues from the digital stereo audio input signal; generating a left-side component and a right-side component from the digital stereo audio input signal, at least partially, in accordance with the localization cues; performing crosstalk cancellation to the left-side component and the right-side component, respectively, to obtain a crosstalk-cancelled left-side component and a crosstalk-cancelled right-side component; and generating a digital stereo audio output signal including the crosstalk-cancelled left-side component and the crosstalk-cancelled right-side component.

## Claims

### Claim 1

A method for processing an audio signal, comprising:
at a computing device having one or more processors, memory, and a plurality of program modules stored in the memory and to be executed by the one or more processors:
receiving a digital audio input signal;
performing equalization to the digital audio input signal by enhancing the digital audio input signal within a predefine frequency range and generating a residual audio signal from the equalized audio signal, wherein performing equalization to the digital audio input signal by enhancing the digital audio input signal within the predetermined frequency range and generating the residual audio signal from the equalized audio signal further comprises:
applying a first bandpass filter to the digital audio input signal to obtain a bandpass-filtered audio signal; and
generating the residual audio signal by subtracting the bandpass-filtered audio signal from the digital audio input signal;
performing dynamic range compression to the equalized audio signal;
performing crosstalk cancellation to the equalized audio signal to obtain a crosstalk-cancelled audio signal; and
combining the crosstalk-cancelled audio signal and the residual audio signal into a digital audio output signal.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
after performing equalization to the equalization to the digital audio input signal using the first bandpass filter:
removing a predefined frequency band from the bandpass-filtered audio signal using a second bandpass filter.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
after performing equalization to the equalization to the digital audio input signal using the first bandpass filter:
performing first dynamic range compression to the bandpass-filtered audio signal to highlight a predefined frequency band with respect to other frequencies.

### Claim 4 (depends on 1)

The method of claim 1, wherein the digital audio input signal is a left channel of a stereo audio input signal that also includes a right channel and the step of performing crosstalk cancellation to the equalized audio signal to obtain a crosstalk-cancelled audio signal further includes:
performing crosstalk cancellation to the left channel using a similarly processed right channel to obtain a crosstalk-cancelled left channel audio signal; and
performing crosstalk cancellation to the right channel using the equalized audio signal to obtain a crosstalk-cancelled right channel audio signal.

### Claim 5

A computing device for processing an audio signal, comprising:
one or more processors;
memory; and
a plurality of program modules stored in the memory and to be executed by the one or more processors, wherein the plurality of program modules, when executed by the one or more processors, cause the computing device to perform a plurality of steps including:
receiving a digital audio input signal;
performing equalization to the digital audio input signal by enhancing the digital audio input signal within a predefine frequency range and generating a residual audio signal from the equalized audio signal, wherein performing equalization to the digital audio input signal by enhancing the digital audio input signal within the predetermined frequency range and generating the residual audio signal from the equalized audio signal further comprises:
applying a first bandpass filter to the digital audio input signal to obtain a bandpass-filtered audio signal; and
generating the residual audio signal by subtracting the bandpass-filtered audio signal from the digital audio input signal;
performing dynamic range compression to the equalized audio signal;
performing crosstalk cancellation to the equalized audio signal to obtain a crosstalk-cancelled audio signal; and
combining the crosstalk-cancelled audio signal and the residual audio signal into a digital audio output signal.

### Claim 6 (depends on 5)

The computing device of claim 5, wherein the plurality of steps further include:
after performing equalization to the equalization to the digital audio input signal using the first bandpass filter:
removing a predefined frequency band from the bandpass-filtered audio signal using a second bandpass filter.

### Claim 7 (depends on 5)

The computing device of claim 5, wherein the plurality of steps further include:
after performing equalization to the equalization to the digital audio input signal using the first bandpass filter:
performing first dynamic range compression to the bandpass-filtered audio signal to highlight a predefined frequency band with respect to other frequencies.

### Claim 8 (depends on 7)

The computing device of claim 7, wherein the digital audio input signal is a left channel of a stereo audio input signal that also includes a right channel and the step of performing crosstalk cancellation to the equalized audio signal to obtain a crosstalk-cancelled audio signal further includes:
performing crosstalk cancellation to the left channel using a similarly processed right channel to obtain a crosstalk-cancelled left channel audio signal; and
performing crosstalk cancellation to the right channel using the equalized audio signal to obtain a crosstalk-cancelled right channel audio signal.

### Claim 9

A non-transitory computer readable storage medium storing a computer program product in connection with a computing device having one or more processors for processing an audio signal, the computer program product including a plurality of program modules that, when executed by the one or more processors, cause the computing device to perform a plurality of steps including:
receiving a digital audio input signal;
performing equalization to the digital audio input signal by enhancing the digital audio input signal within a predefine frequency range and generating a residual audio signal from the equalized audio signal, wherein performing equalization to the digital audio input signal by enhancing the digital audio input signal within the predetermined frequency range and generating the residual audio signal from the equalized audio signal further comprises:
applying a first bandpass filter to the digital audio input signal to obtain a bandpass-filtered audio signal; and
generating the residual audio signal by subtracting the bandpass-filtered audio signal from the digital audio input signal;
performing dynamic range compression to the equalized audio signal;
performing crosstalk cancellation to the equalized audio signal to obtain a crosstalk-cancelled audio signal; and
combining the crosstalk-cancelled audio signal and the residual audio signal into a digital audio output signal.

### Claim 10 (depends on 9)

The non-transitory computer readable storage medium of claim 9, wherein the plurality of steps further include:
after performing equalization to the equalization to the digital audio input signal using the first bandpass filter:
removing a predefined frequency band from the bandpass-filtered audio signal using a second bandpass filter.

### Claim 11 (depends on 9)

The non-transitory computer readable storage medium of claim 9, wherein the plurality of steps further include:
after performing equalization to the equalization to the digital audio input signal using the first bandpass filter:
performing first dynamic range compression to the bandpass-filtered audio signal to highlight a predefined frequency band with respect to other frequencies.

### Claim 12 (depends on 11)

The non-transitory computer readable storage medium of claim 11, wherein the digital audio input signal is a left channel of a stereo audio input signal that also includes a right channel and the step of performing crosstalk cancellation to the equalized audio signal to obtain a crosstalk-cancelled audio signal further includes:
performing crosstalk cancellation to the left channel using a similarly processed right channel to obtain a crosstalk-cancelled left channel audio signal; and
performing crosstalk cancellation to the right channel using the equalized audio signal to obtain a crosstalk-cancelled right channel audio signal.