MMSE-Based Blind Source Extraction in Diffuse Noise Fields Using a Complex Coherence-Based a Priori SAP Estimator

In many practical situations we can assume that the desired sound is strongly coherent across the microphone array and it is corrupted by diffuse noise. We propose an algorithm to extract such desired sounds without prior knowledge of the noise power spectral density (PSD) matrix or the direction of arrival of the desired source(s). We first propose a multichannel noise PSD matrix estimator that is based on the speech presence probability. To differentiate between desired and noise signals, we propose to control the a priori speech absence probability using an estimate of the direct to diffuse ratio (DDR). We then obtain an estimate of the desired signal using a parametric multichannel Wiener filter that allows a trade-off between noise reduction and speech distortion. We demonstrate that the noise reduction can be increased and the speech distortion can be decreased by controlling the trade-off parameter using the estimated DDR.