Voice characteristics conversion for TTS using reverse VTLN

Abstract

In the past, several approaches have been proposed for voice conversion in TTS systems. Mostly, conversion is done by modification of the spectral properties and pitch to match a certain target voice. This conversion causes distortions that deteriorate the quality of the synthesized speech. In this paper we investigate a very simple and straightforward method for voice conversion. It generates a new voice from the source speaker instead of generating a certain target speaker's voice. For application in TTS systems it is often sufficient to synthesize new voices that sound sufficiently different to be distinguishable from each other. This is done by applying a spectral warping technique that is commonly used for speaker normalization in speech recognition systems called vocal tract length normalization (VTLN). Due to the low requirements of resources this method is especially suited for embedded systems.