Extension of the local subspace method to enhancement of speech with colored noise

Based on dynamic features of human speech, the local projection (LP) method has been adapted to the enhancement of speech corrupted by white noise. As an extension of the LP method, a strategy with two rounds of projection is introduced to enhance the speech contaminated with colored noise. Colored noise mainly resides in a low dimensional subspace, and is assumed to be stationary in this communication. At step one, a noise dominated subspace is first estimated with colored noise obtained from speech silence frame. Then for the reference phase point, the components, projected into the noise dominated subspace, are deleted and the enhanced speech is reconstructed with the remaining components. The residual error of the output of step one tends to distribute uniformly on each direction. So at step two, the LP method is further applied to the output of step one, treating the residual error as white noise. An adaption of this strategy to continuous speech is performed. The results show that this strategy is more effective than the LP method in enhancing speech corrupted by colored noise, and is comparable to two typical speech enhancement methods.