Nonlinear echo suppression
Presented is a method and associated system for suppression of linear and nonlinear echo. The method includes dividing an input signal into several frequency bands in each of a several of time frames. The input signal may include an echo signal. The method further includes multiplying the input signal in each of the several frequency bands by a corresponding echo suppression signal. Calculating the corresponding echo suppression signal may include estimating a power of the echo signal in a particular frequency band as a sum of several component echo powers, each of the several component echo powers due to an excitation from a far-end signal in a corresponding one of the several frequency bands. Calculating the corresponding echo suppression signal may further include subtracting the power of the echo signal in the particular frequency band from a power of the input signal in the particular frequency band.
1. A method for echo suppression, said method comprising:
dividing an input signal into a plurality of frequency bands in each of a plurality of time frames, said input signal comprising an echo signal;
multiplying said input signal in each of said plurality of frequency bands by a corresponding echo suppression signal, wherein calculating said corresponding echo suppression signal comprises:
estimating a power of said echo signal in a particular frequency band as a sum of a plurality of component echo powers, each of said plurality of component echo powers due to an excitation from a far-end signal in a corresponding one of said plurality of frequency bands; and
subtracting said power of said echo signal in said particular frequency band from a power of said input signal in said particular frequency band;
wherein estimating each of said plurality of component echo powers comprises:
applying a delay to said far-end signal in said corresponding one of said plurality of frequency bands; and
applying a weight to said far-end signal in said corresponding one of said plurality of frequency bands.
2. The method of claim 1 , wherein said calculating said corresponding echo suppression signal further comprises dividing by said power of said input signal in said particular frequency band.
3. The method of claim 1 , wherein said echo signal is a residual echo signal from a linear echo canceller.
4. The method of claim 1 , wherein said plurality of component echo powers are uncorrelated with one another.
5. The method of claim 1 , wherein said delay is chosen to maximize a cross-correlation between said input signal and said far-end signal in said corresponding one of said plurality of frequency bands.
6. The method of claim 1 , wherein said weight is a normalized cross-correlation between said input signal in said particular frequency band and said far-end signal in said particular frequency band.
7. A method for echo suppression, said method comprising:
dividing an input signal into a plurality of frequency bands in each of a plurality of time frames, said input signal comprising an echo signal;
multiplying said input signal in each of said plurality of frequency bands by a corresponding echo suppression signal, wherein calculating said corresponding echo suppression signal comprises:
estimating a power of said echo signal in a particular frequency band as a sum of a plurality of component echo powers, each of said plurality of component echo powers due to an excitation from a far-end signal in a corresponding one of said plurality of frequency bands; and
subtracting said power of said echo signal in said particular frequency band from a power of said input signal in said particular frequency band;
wherein said echo signal is a residual echo signal from a linear echo canceller, and wherein estimating each of said plurality of component echo powers comprises:
applying a weight to a synthesized echo in said corresponding one of said plurality of frequency bands, said synthesized echo obtained from a linear echo canceller.
8. The method of claim 7 , wherein said weight is a normalized cross-correlation between said input signal in said particular frequency band and said synthesized echo in said corresponding one of said plurality of frequency bands.
9. The method of claim 1 , wherein said plurality of component echo powers comprise only component echo powers due to an excitation from said far-end signal in said corresponding one of said plurality of frequency bands, in a frequency band having a frequency of one half of said corresponding one of said plurality of frequency bands, and in a frequency band having a frequency of one third of said corresponding one of said plurality of frequency bands.