Go To Program 90 Influence of Blocking Matrix Design on Microphone Array Postfilters Tobias Wolff 1 Markus Buck 1 1 Nuance Communications Aachen GmbH, Germany In this paper the role of the blocking matrix is investigated in the context of microphone array postfilters. A generic stability criterion, which depends on the blocking matrix, is given and discussed. This allows a new view on the causes of postfilter instability. The performance of non-adaptive and adaptive blocking matrix implementations is investigated for a car environment. Finally, the impact of these matrices on the postfilter performance is analyzed. The results suggest, that an adaptive implementation of the blocking matrix is a way to substantially improve the speech quality delivered by the beamformer-postfilter system. View pdf