A Novel Method for Prosody Prediction in Voice Conversion

Most of the published voice conversion schemes do not consider detailed prosody modeling but only control the F0 level and range. However, the detailed prosody can also carry a significant amount of speaker identity related information. This paper introduces a new method for converting the prosody in voice conversion. A syllable-based prosodic codebook is used to predict the converted F0 using not only the source contour but also linguistic information and segmental durations. The selection of the most suitable target contour is carried out using a trained classification and regression tree. The F0 contours in the codebook are represented in a transformed domain which allows compression and fast comparison. The performance of the prosodic conversion is evaluated in a real voice conversion system. The results indicate a significant improvement in speaker identity and naturalness when compared to GMM (Gaussian mixture model) based pitch prediction approach.