Speech enhancement combining spectral subtraction and beamforming techniques for microphone array

Abstract

In all speech communication settings the quality and intelligibility of speech is of utmost importance for ease and accuracy of information exchange. The Spectral Subtraction Technique is one of the methods to reduce stationary noise but the non stationary noise still passes through it. Spectral Subtraction also introduces a musical noise which is very annoying to human ears. Beamforming is another possible method of speech enhancement that can be used. Beamforming by itself, however, does not appear to provide enough improvement. Further, the performance of Beamforming becomes worse if the noise source comes from many directions or the speech has strong reverberation. A combined technique using the advantages of Spectral Subtraction and Beamforming Techniques is proposed where the Spectral Subtraction Technique followed by Beamforming Technique reduces stationary as well as residual, musical noise. It can be observed that the Spectral Subtraction followed by Beamforming gives better SNR value as compared to that of individual techniques, thereby improving the quality of speech. Numerous simulation results are used to illustrate the reasoning.