Voice conversion through transformation of spectral and intonation features

This paper presents a voice conversion method based on transformation of the characteristic features of a source speaker towards a target. Voice characteristic features are grouped into two main categories: (a) the spectral features at formants and (b) the pitch and intonation patterns. Signal modelling and transformation methods for each group of voice features are outlined. The spectral features at formants are modelled using a set of two-dimensional phoneme-dependent HMM. Subband frequency warping is used for spectrum transformation with the subbands centred on the estimates of the formant trajectories. The F0 contour is used for modelling the pitch and intonation patterns of speech. A PSOLA based method is employed for transformation of pitch, intonation patterns and speaking rate. The experiments present illustrations and perceptual evaluations of the results of transformations of the various voice features.