Speech Enhancement Employing Adaptive Beamformer with Recursively Updated Soft Constraints

A novel adaptive beamformer employing recursively updated soft constraints for acoustic speech enhancement is proposed. The beamformer operates in a subband structure to allow a time-frequency operation for each channel. Consequently, the processing performed can be viewed as a combined weighted spatial,frequency and temporal filter. The major benefit of the new recursive soft constrained beamformer is that it allows the possibility of using the spectral information of the desired source to modify the soft constraint. This has clear benefits on the speech distortion of the source of interest. The novel adaptive beamformer involves continuous modification of the soft constraint by feeding back the spectral content of the estimated output speech signal. Evaluations of the proposed beamformer based on real car data show that the proposed algorithm significantly improves the speech quality with noise suppression levels up to 17 dB.