Stephen D. Voran

Abstract: Separating an acoustic signal into desired and undesired components is an important and well-established problem. It is commonly addressed by decomposing spectral magnitudes after exponentiation and the choice of exponent has been studied from numerous perspectives. We present this exponent selection problem as an approximation to the actual underlying geometric situation. This approach makes apparent numerous basic facts and some of these have been ignored or violated in related work efforts. We show that exponent selection is dominated by the phase distribution and that magnitude distributions have almost no influence. We also show that exponents can be much more effectively selected in the estimated source domain, rather than in the domain of the combined sources. Finally we describe the mechanism that causes exponents slightly above 1.0 to be preferred in many cases, completely independent of source distributions

Keywords: noise reduction; speech enhancement; source separation; spectral subtraction; spectral magnitude exponent

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