Control and prediction of the impact of pitch modification on synthetic speech quality

In order to use speech synthesis to generate highly expressive speech convincingly, the problem of poor prosody (both prediction and generation) needs to be overcome. In this paper we will show that with a simple annotation scheme using the notion of foot structure, we can more accurately predict the shape of local pitch contours. The assumption is that with a better selection mechanism we can reduce the amount of pitch modification required, thereby reducing speech degradation. In addition, we present a perceptual experiment that investigates the degradation introduced by pitch modification using the OGIresLPC algorithm. We correlated the weighted perceptual score with different pitch and delta pitch distances. The best combination of distance measures is able to explain 63% of the variance in the perceptual scores. Decreasing the pitch is shown to have a higher impact on perception than increasing the pitch.