Method and system for clear signal capture
First Claim
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1. A method of acoustic echo cancellation (AEC) wherein a microphone signal resulting from an unobservable signal corrupted by both additive background noise and an acoustic echo is processed in an attempt to restore the unobservable signal, the acoustic echo being a speaker signal modified by an acoustic path, wherein an adaptive filter models the echo path, the method comprising:
- receiving the microphone signal;
applying a first asymmetric nonlinear adaptive filter in fullband to the speaker signal to produce a first output signal;
applying a first adaptive filter in fullband to the first output signal to produce a first echo signal that models the acoustic echo;
subtracting the first echo signal from the microphone signal to produce a first echoless signal that resembles the unobservable signal; and
adapting the first nonlinear adaptive filter in fullband and the first adaptive filter based on the first echoless signal.
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Abstract
A method and system for clear signal capture comprehend several individual aspects that address specific problems in improved ways. In addition, the method and system also comprehend a hands-free implementation that is a practical solution to a very complex problem.
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Citations
24 Claims
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1. A method of acoustic echo cancellation (AEC) wherein a microphone signal resulting from an unobservable signal corrupted by both additive background noise and an acoustic echo is processed in an attempt to restore the unobservable signal, the acoustic echo being a speaker signal modified by an acoustic path, wherein an adaptive filter models the echo path, the method comprising:
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receiving the microphone signal;
applying a first asymmetric nonlinear adaptive filter in fullband to the speaker signal to produce a first output signal;
applying a first adaptive filter in fullband to the first output signal to produce a first echo signal that models the acoustic echo;
subtracting the first echo signal from the microphone signal to produce a first echoless signal that resembles the unobservable signal; and
adapting the first nonlinear adaptive filter in fullband and the first adaptive filter based on the first echoless signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of acoustic echo cancellation (AEC) wherein a microphone signal resulting from an unobservable signal corrupted by both additive background noise and an acoustic echo is processed in an attempt to restore the unobservable signal, the acoustic echo being a speaker signal modified by an acoustic path, wherein an adaptive filter in frequency domain models the echo path, the method including receiving the microphone signal, applying an adaptive filter in subbands to the speaker signal to produce an echo signal that models the acoustic echo, subtracting the echo signal from the microphone signal to produce a frequency domain echoless signal that resembles the unobservable signal, and adapting the adaptive filter based on the frequency domain echoless signal, the method further comprising:
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applying a residual echo reduction filter to the frequency domain echoless signal;
determining an average bandwidth attenuation factor based on the coefficients of the residual echo reduction filter;
determining a threshold; and
when the average bandwidth attenuation factor is less than the threshold, applying a frequency dependent nonlinear attenuation vector to a defined group of frequency bands. - View Dependent Claims (11)
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12. A method of acoustic echo cancellation (AEC) wherein a microphone signal resulting from an unobservable signal corrupted by both additive background noise and an acoustic echo is processed in an attempt to restore the unobservable signal, the acoustic echo being a speaker signal modified by an acoustic path, wherein an adaptive filter in frequency domain models the echo path, the method including receiving the microphone signal, applying an adaptive filter in subbands to the speaker signal to produce an echo signal that models the acoustic echo, subtracting the echo signal from the microphone signal to produce a frequency domain echoless signal that resembles the unobservable signal, and adapting the adaptive filter based on the frequency domain echoless signal, the method further comprising:
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making a classification of near-end and far-end speeches to detect a significant nonlinear relationship between near-end and far-end speeches; and
in the event that a significant nonlinear relationship is detected, increasing the adaptation rate of the adaptive filter in frequency domain to escape local minima and approach the global minima. - View Dependent Claims (13, 14)
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15. A method of acoustic echo cancellation (AEC) wherein a microphone signal resulting from an unobservable signal corrupted by both additive background noise and an acoustic echo is processed in an attempt to restore the unobservable signal, the acoustic echo being a speaker signal modified by an acoustic path, wherein an adaptive filter in frequency domain models the echo path, the method including receiving the microphone signal, applying an adaptive filter in subbands to the speaker signal to produce an echo signal that models the acoustic echo, subtracting the echo signal from the microphone signal to produce a frequency domain echoless signal that resembles the unobservable signal, and adapting the adaptive filter based on the frequency domain echoless signal, the method further comprising:
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applying a residual echo reduction filter to the frequency domain echoless signal;
utilizing state differentiators to make a classification of near-end and far-end speeches to detect a significant nonlinear relationship between near-end and far-end speeches; and
in the event that a significant nonlinear relationship is detected, modifying the residual echo reduction filter to provide additional attenuation to the residual echo relative to the extent of attenuation provided in the absence of significant nonlinearity. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A method of acoustic echo cancellation (AEC) wherein a microphone signal resulting from an unobservable signal corrupted by both additive background noise and an acoustic echo is processed in an attempt to restore the unobservable signal, the acoustic echo being a speaker signal modified by an acoustic path, wherein an adaptive filter models the echo path, the method including receiving the microphone signal, applying an adaptive filter to the speaker signal to produce an echo signal that models the acoustic echo, subtracting the echo signal from the microphone signal to produce a first echoless signal that resembles the unobservable signal, and adapting the adaptive filter based on the first echoless signal, the method further comprising:
prior to the input of the adaptive filter, a nonlinear compensation scaled by volume information of the system, is applied to the input signal to produce a new input of the adaptive filter and the speaker signal, whereby this dynamic nonlinear pre-distoration allows the system to be treated as a linear system. - View Dependent Claims (22, 23, 24)
Specification