Distributed GSC beamforming using the relative transfer function

A speech enhancement algorithm in a noisy and reverberant enclosure for a wireless acoustic sensor network (WASN) is derived. The proposed algorithm is structured as a two stage beamformers (BFs) scheme, where the outputs of the first stage are transmitted in the network. Designing the second stage BF requires estimating the desired signal components at the transmitted signals. The contribution here is twofold. First, in spatially static scenarios, the first stage BFs are designed to maintain a fixed response towards the desired signal. As opposed to competing algorithms, where the response changes and repeated estimation thereof is required. Second, the proposed algorithm is implemented in a generalized side-lobe canceler (GSC) form, separating the treatment of the desired speech and the interferences and enabling a simple time-recursive implementation of the algorithm. A comprehensive experimental study demonstrates the equivalent performance of the centralized GSC and of the proposed algorithm for both narrowband and speech signals.