Perceptual masking of residual echo
View Patent ↗A method of masking a residual echo signal by an echo canceller is provided. The method comprises receiving a far-end signal, adjusting filter coefficients of an adaptive filter in response to the far-end signal, generating an echo model signal based on the far-end signal using the adaptive filter, receiving a near-end signal, subtracting the echo model signal from the near-end signal to generate an output signal, defining a spectral mask based on the near-end signal, wherein the spectral mask is indicative of near-end spectral peaks and near-end spectral valleys, de-emphasizing the output signal in spectral regions of the near-end spectral peaks, and emphasizing the output signal in spectral regions of the near-end spectral valleys, wherein the de-emphasizing occurs during filter coefficients determination for the adaptive filter. A weighted filter may perform the de-emphasizing and the emphasizing operations, where the weighted filter uses medium term spectral characteristics of the near-end signal.
1. A method of masking a residual echo signal by an echo canceller, said method comprising:
receiving a far-end signal;
adjusting filter coefficients of an adaptive filter in response to said far-end signal;
generating an echo model signal based on said far-end signal using said adaptive filter;
receiving a near-end signal;
subtracting said echo model signal from said near-end signal to generate an output signal;
defining a spectral mask based on said near-end signal, wherein said spectral mask is indicative of near-end spectral peaks and near-end spectral valleys;
de-emphasizing said output signal in spectral regions of said neat-end spectral peaks, using a weighted filter based on medium term spectral characteristics of said near-end signal; and
emphasizing said output signal in spectral regions of said near-end spectral valleys.
2. The method of claim 1 , wherein an inverse of said weighted filter generates a signal that is correlated with said medium term spectral characteristics of said near-end signal.
3. The method of claim 1 , wherein said medium term spectral characteristics of said near-end signal are estimated in absence of echo.
4. The method of claim 1 further comprises applying a spectral post-processing to said output signal to decrease or remove choppiness.
5. An echo cancellation system for masking a residual echo signal, said echo cancellation system comprising:
a far-end receiver configured to receive a far-end signal;
an adaptive filter configured to adjust filter coefficients in response to said far-end signal, said adaptive filter further configured to generate an echo model signal based on said far-end signal;
a near-end receiver configured to receive a near-end signal;
a subtractor configured to subtract said echo model signal from said near-end signal to generate an output signal; and
a mask generator configured to define a spectral mask based on said near-end signal, wherein said spectral mask is indicative of near-end spectral peaks and near-end spectral valley, and wherein said mask generator is further configured to de-emphasize said output signal in spectral regions of said near-end spectral peaks and to emphasize said output signal in spectral regions of said near-end spectral valleys, wherein said mask generator includes a weighted filter, and wherein said weighted filter de-emphasizes said output signal in spectral regions of said near-end spectral peaks and emphasizes said output signal in spectral regions of said near-end spectral valleys, wherein said weighted filter uses medium term spectral characteristics of said near-end signal.
6. The echo cancellation system of claim 5 , wherein an inverse of said weighted filter generates a signal that is correlated with said medium term spectral characteristics of said near-end signal.
7. The echo cancellation system of claim 5 , wherein said medium term spectral characteristics of said near-end signal are estimated in absence of echo.
8. The echo cancellation system of claim 5 further comprises a spectral post-processor configured to apply a spectral post-processing to said output signal to decrease or remove choppiness.
9. A computer program stored in a computer-readable medium for execution by an echo cancellation system for masking a residual echo signal, said computer program comprising:
code for receiving a far-end signal;
code for adjusting filter coefficients of an adaptive filter in response to said far-end signal;
code for generating an echo model signal based on said far-end signal using said adaptive filter;
code for receiving a near-end signal;
code for subtracting said echo model signal from said near-end signal to generate an output signal;
code for defining a spectral mask based on said near-end signal, wherein said spectral mask is indicative of near-end spectral peaks and near-end spectral valleys;
code for de-emphasizing said output signal in spectral regions of said near-end spectral peaks, using a weighted filter based on medium term spectral characteristics of said near-end signal; and
code for emphasizing said output signal in spectral regions of said near-end spectral valleys.
10. The computer program of claim 9 , wherein said medium term spectral characteristics of said near-end signal are estimated in absence of echo.
11. The computer program of claim 9 further comprises code for applying a spectral post-processing to said output signal to decrease or remove choppiness.