Voice conversion based on parameter transformation

This paper describes a voice conversion system based on parameter transformation [1]. Voice conversion is the process of making one person’s voice “source” sound like another person’s voice “target”[2]. We will present a voice conversion scheme consisting of three stages. First an analysis is performed on the natural speech to obtain the acoustical parameters. These parameters will be voiced and unvoiced regions, the glottal source model, pitch, energy, formants and bandwidths. Once these parameters have been obtained for two different speakers they are transformed using linear functions. Finally the transformed parameters are synthesized by means of a formant synthesizer. Experiments will show that this scheme is effective in transforming the speaker individuality. It will also be shown that the transformation can not be unique from one speaker to another but it has to be divided in several functions each to transform a certain part of the speech signal. Segmentation based on spectral stability will divide the sentence into parts, for each segment a transformation function will be applied.