Non-uniform adaptive echo cancellation
First Claim
Patent Images
1. A system, comprising:
- one or more input filters configured to decompose a microphone signal into a plurality of input sub-signals corresponding respectively to different frequency bands;
one or more reference filters configured to decompose a reference audio signal into a plurality of reference sub-signals corresponding respectively to the different frequency bands;
a plurality of echo cancellers corresponding respectively to the different frequency bands, wherein the echo canceller corresponding to each frequency band is configured to suppress echoes in an input sub-signal corresponding to a frequency band based at least in part on a reference sub-signal corresponding to the frequency band to produce an echo-suppressed input sub-signal corresponding to the frequency band;
a signal synthesizer configured to synthesize an echo-suppressed output audio signal by summing the produced echo-suppressed input sub-signals; and
wherein a first adaptive finite impulse response filter of a first of the echo cancellers has a first filter order and a second adaptive finite impulse response filter of a second of the echo cancellers has a second filter order that is different than the first filter order; and
wherein the first filter order and the second filter order are based at least in part on a power of the reference sub-signal corresponding to the first of the echo cancellers in relation to an average of the powers of the reference sub-signals of the different frequency bands.
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Abstract
An audio-based system may perform echo cancellation by decomposing an input audio signal and a corresponding reference signal into sub-signals corresponding to different frequency bands and implementing adaptive filtering independently for each frequency band. Computational resources may be allocated differently for each of the frequency bands depending on observed conditions. Orders of adaptive FIR filters may be varied during operation. Double talk detection and echo path change detection may be implemented for some frequency bands and not others. Filter adaption rates may also be assigned independently to each of the FIR filters, and may be changed during operation.
20 Citations
21 Claims
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1. A system, comprising:
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one or more input filters configured to decompose a microphone signal into a plurality of input sub-signals corresponding respectively to different frequency bands; one or more reference filters configured to decompose a reference audio signal into a plurality of reference sub-signals corresponding respectively to the different frequency bands; a plurality of echo cancellers corresponding respectively to the different frequency bands, wherein the echo canceller corresponding to each frequency band is configured to suppress echoes in an input sub-signal corresponding to a frequency band based at least in part on a reference sub-signal corresponding to the frequency band to produce an echo-suppressed input sub-signal corresponding to the frequency band; a signal synthesizer configured to synthesize an echo-suppressed output audio signal by summing the produced echo-suppressed input sub-signals; and wherein a first adaptive finite impulse response filter of a first of the echo cancellers has a first filter order and a second adaptive finite impulse response filter of a second of the echo cancellers has a second filter order that is different than the first filter order; and wherein the first filter order and the second filter order are based at least in part on a power of the reference sub-signal corresponding to the first of the echo cancellers in relation to an average of the powers of the reference sub-signals of the different frequency bands. - View Dependent Claims (2, 3, 4, 18)
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5. A method, comprising:
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decomposing an input audio signal into a plurality of input sub-signals corresponding respectively to different frequency bands; decomposing a reference audio signal into a plurality of reference sub-signals corresponding respectively to the different frequency bands; suppressing echo components of each input sub-signal based at least in part on the reference sub-signal corresponding to a same frequency band as the input sub-signal to produce echo-suppressed input sub-signals corresponding respectively to the different frequency bands; dynamically allocating computational resources for the suppressing based at least in part on a power of at least the reference sub-signal, wherein greater computational resources are allocated for suppressing the echo components of a first of the input sub-signals than are allocated for suppressing the echo components of a second of the input sub-signals; and synthesizing an echo-suppressed output audio signal from the echo-suppressed input sub-signals. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
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13. A method, comprising:
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decomposing an input audio signal into a plurality of input sub-signals corresponding respectively to different frequency bands, wherein a first input sub-signal, from the plurality of input sub-signals, represents audio data of a first frequency band; decomposing a reference audio signal into a plurality of reference sub-signals corresponding respectively to the different frequency bands, wherein a first reference sub-signal, from the plurality of reference sub-signals, represents audio data of the first frequency band; suppressing echo components of the first input sub-signal based at least in part on the first reference sub-signal to produce a first echo-suppressed input sub-signal corresponding to the first frequency band; calculating a variable adaptation rate based at least in part on power of the first reference sub-signal and power of the first echo-suppressed input sub-signal, wherein the suppressing comprises adaptively filtering the first input sub-signal using the variable adaptation rate; and synthesizing a first echo-suppressed output audio signal from the first echo-suppressed input sub-signal. - View Dependent Claims (14, 15, 16, 17, 19)
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20. A system, comprising:
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one or more input filters configured to decompose a microphone signal into a plurality of input sub-signals corresponding respectively to different frequency bands; one or more reference filters configured to decompose a reference audio signal into a plurality of reference sub-signals corresponding respectively to the different frequency bands; a plurality of echo cancellers corresponding respectively to the different frequency bands, wherein the echo canceller corresponding to each frequency band is configured to suppress echoes in an input sub-signal corresponding to a frequency band based at least in part on a reference sub-signal corresponding to the frequency band to produce an echo-suppressed input sub-signal corresponding to the frequency band; a signal synthesizer configured to synthesize an echo-suppressed output audio signal by summing the produced echo-suppressed input sub-signals; and wherein a first adaptive finite impulse response filter of a first of the echo cancellers has a first filter order and a second adaptive finite impulse response filter of a second of the echo cancellers has a second filter order that is different than the first filter order; and wherein the first filter order and the second filter order are based at least in part on a power estimation of the echo-suppressed sub-signal in relation to a power estimation of near-end audio in the input sub-signal. - View Dependent Claims (21)
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Specification