Echo cancellation and noise reduction method
View Patent ↗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. Individual aspects comprehended related to echo and noise reduction, and divergence control.
1. A method of acoustic echo cancellation (AEC) and noise cancellation (NC) 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 in the frequency domain, and wherein a noise cancellation filter is implemented in the frequency domain, the method comprising:
receiving the microphone signal;
applying the adaptive filter to the speaker signal to produce an echo signal that models the acoustic echo;
applying the noise cancellation filter to the microphone signal to produce an NC-filtered microphone signal;
applying a copy of the noise cancellation filter to the echo signal to produce an NC-filtered echo signal;
subtracting the NC-filtered echo signal from the NC-filtered microphone signal to produce a first echoless signal that resembles the unobservable signal; and
adapting the adaptive filter based on the first echoless signal.
2. The method of claim 1 wherein processing takes place independently in a plurality of subbands.
3. The method of claim 1 wherein the adaptive filter utilizes a data reuse normalized least mean square adaptive filter algorithm.
4. The method of claim 1 further comprising:
subtracting the echo signal from the microphone signal to produce a second echoless signal; and
applying a second noise cancellation filter to the second echoless signal to produce an output signal that resembles the unobservable signal.