Voice conversion with pitch alteration using phase vocoder

摘要

A novel approach to pitch transposition is presented, which allows to preserve the spectral envelope or to modify it in a voice conversion task. Pitch-shifted output is synthesized directly from the input signal using the phase vocoder, without explicitly estimating the fundamental frequency, which is often prone to errors. Frequency band extension technique is proposed to address the problem of bandwidth reduction when scaling pitch down. Artificial neural network was applied to transform the signal's spectral envelope in the full voice conversion task. Listening tests showed that 55% of listeners preferred the quality of the pitch modification using the phase vocoder over the one offered by a parametric approach.