A microphone array processing technique for speech enhancement in a reverberant space

Abstract

In this paper, a new microphone array processing technique is proposed for blind dereverberation of speech signals affected by room acoustics. It is based on the separate processing of the minimum-phase and all-pass components of delay-steered multi-microphone signals. The minimum-phase components are processed in the cepstrum-domain, where spatial averaging followed by low-time filtering is applied. The all-pass components, which contain the source location information, are processed in the frequency-domain by performing spatial averaging and by retaining only the all-pass component of the resulting output. The underlying motivation for the new processor is to use spatio-temporal processing over a single set of synchronous speech segments from several microphones to reconstruct the source speech, such that it is applicable to practical time-variant acoustic environments. Simulated room impulse responses are used to evaluate the new processor and to compare it to a conventional beamformer. Significant improvements in array gain and important reductions of reverberation in listening tests are observed.