A two-channel reverberation suppression scheme based on blind signal separation and wiener filtering

In this paper, we apply a blind signal extraction scheme for two microphones to the problem of dereverberation. The system consists of a blocking matrix that cancels the target signal as well as reverberated components up to a certain time lag, thus obtaining a reference not only for noise and interference, but also for late reverberation, which can then be suppressed with a Wiener filter, while leaving early reverberation components largely intact. The performance is assessed in terms of recognition rate of an automatic speech recognizer trained on clean speech, using sentences from the GRID corpus convolved with measured room impulse responses. We show that the system, although primarily developed for noise and interference suppression in low SNR conditions, can significantly suppress reverberation and thereby improve recognition results.