On speech enhancement under signal presence uncertainty

In this paper, we present an optimally-modified log-spectral amplitude estimator, which minimizes the mean-square error of the log-spectra for speech signals under signal presence uncertainty. The spectral gain function is obtained as a weighted geometric mean of the hypothetical gains associated with signal presence and absence. The exponential weight of each hypothetical gain is its corresponding probability, conditioned on the observed signal. We introduce an efficient estimation approach for the a priori signal absence probability in each frequency bin, which exploits the strong correlation of speech presence in neighboring frequency bins of consecutive frames. Objective and subjective evaluation confirm superiority in noise suppression and quality of the enhanced speech