Residual Echo Reduction for Multichannel Acoustic Echo Cancelers With a Complex-Valued Residual Echo Estimate

This paper proposes a new method to reduce residual echo for multichannel acoustic echo cancelers (AECs). This method estimates complex-valued residual echo and corrects its overestimated amplitude on the basis of a bias model of coherence estimation. Unlike conventional residual echo reduction methods for single-channel AECs, this method takes into account not only the magnitudes but also the phases of far-end signals and frequency responses. The inclusion of the phases gives the correct model of residual echo for multichannel AECs. The correction of the overestimated amplitude of residual echo decreases the distortion of near-end speech during double talk. The proposed method reduces the residual echo in the AEC output by 5-10 dB immediately after environmental changes such as a far-end talker change and an echo-path change. The proposed method provides less distorted near-end speech than the square-root Wiener filter during double talk.