Study on combining multi-channel echo cancellers with beamformers

In this paper, we compare different combinations of a multi-channel non-adaptive noise reduction unit (NRU) and an acoustic echo cancellation unit (AEC) for a standard single-channel voice transmission. The results show that the NRU and the AEC-unit can be interchanged without increasing the computational complexity of the combined system, The length of an AEC's adaptive filter can be greatly reduced, if a multi-channel AEC-unit in front of a multichannel NRU is used. Furthermore, the control information, like the step-size of the NLMS-algorithm, has to be computed only once.