Multimicrophone speech dereverberation using spatiotemporal and spectral processing

Speech signals acquired in a reverberant room with microphones positioned at a distance from the talker are degraded in quality due to reverberation and measurement noise. Therefore, enhancement of reverberant speech is important in hands-free telecommunications applications. The perceptual effects of reverberation can be linked to the room impulse response (RIR) between the talker and the microphone and are characterized by: (i) colouration, due to the strong early reflections and (ii) a distant ´echoey´ quality due to the decaying tail of the RIR. Accordingly, we present a two-stage multimicrophone method for speech dereverberation. First, spatiotemporal averaging is performed on the linear prediction residual, which primarily reduces the effects of the early reflections. Secondly, a spectral subtraction method is employed to reduce late reverberation. Simulation results with measured RIRs and additive white Gaussian noise illustrate the performance of this method and show that the combined approach performs better than each of the two stages individually.