An acoustic human-machine interface with multi-channel sound reproduction

For hands-free man-machine audio interfaces with multichannel sound reproduction and automatic speech recognition (ASR), sometimes both an acoustic echo canceller (AEC) and a beamforming (BF) microphone array are necessary for sufficient recognition rates. In the context of multimedia systems, multi-channel sound reproduction (e.g. stereo or 5.1 channel-surround systems) typically requires multi-channel AEC (M-C AEC). With M-C AEC being known to be a very demanding problem in signal processing, no practically relevant simulation results have yet been presented for more than two channels. We examine a previously proposed frequency-domain adaptive filtering scheme with some extensions for the case of more than two loudspeaker channels. The results using this approach show a remarkable performance at a relatively moderate computational complexity. Moreover, we show how to efficiently combine this M-C AEC structure with microphone arrays.