Performance of adaptive dereverberation techniques using directivity controlled arrays

The use of optimal postfiltering has been previously proposed to increase the performance of microphone arrays. In this paper, an analysis of the postfilter shows that its behaviour is closely related to the one of the array. This is illustrated by considering a typical videoconferencing context. The results we provide demonstrate that the use of a directivity controlled array is a requirement to ensure a sufficient robustness of the whole system. It is also shown that the dereverberation performed by the postfilter is limited and that its main interest lies in a significant reduction of the acoustic echo even in the double talk case. This attractive property depends on the whole design of the array including its placement versus the acoustic echo sources.