Enhancement of Residual Echo for Improved Frequency-Domain Acoustic Echo Cancellation

This paper explores the technique of integrating a noise suppressing nonlinearity to the adaptive filter error feedback loop of the frequency-domain acoustic echo canceler (AEC) when there is a continuous additive noise at the near-end. It was shown in a previous study that in the time-domain AEC case, both the echo return loss enhancement (ERLE) and the misalignment from using normalized least-mean-squares (NLMS) can be improved through the error enhancement procedure. By applying the same technique to the frequency-domain AEC, namely the generalized multidelay filter (GMDF), the misalignment can be decreased by around 5 dB on average in a numerical simulation, whereas the ERLE can be increased by 2 dB on average and by over 5 dB at some instances in a real acoustic environment. New results further support the idea that reducing the effects of distortion to the cancellation error helps to improve the performance of an adaptive filter.