A nested superdirective generalized sidelobe canceller for speech enhancement

This paper deals with the problem of microphone array speech enhancement using a hybrid Generalized Sidelobe Canceller (GSC) and Super-Directive Beamformer (SDB). While GSC is one of the most practical architectures for reducing the directional noises, SDB is a superior choice in the case of diffuse noise fields. In this research, we have combined these two structures to improve the performance of speech enhancement system in realistic noisy conditions. Furthermore, we have employed a Linear Constrained Minimum Variance (LCMV) beamformer instead of blocking matrix (in GSC) to generalize the good performance of the system for different arrival directions of desired speech. Finally, we have proposed nested sub-array implementation of the hybrid system to take advantages of the subband processing of wideband speech signal. Our experiments show the effectiveness of the proposed modifications in different input SNR values. The comparative evaluations demonstrate the superiority of the proposed system in noise reduction from speech in real-life conditions (where diffuse, incoherent, and directional noises are present, simultaneously).