Segmental duration control based on an articulatory model

This paper proposes a new method that determines segmental duration for text-to-speech conversion based on the movement of articulatory organs which compose an articulatory model. The articulatory model comprises four time-variable articulatory parameters representing the conditions of articulatory organs whose physical restriction seems to significantly influence the segmental duration. The parameters are controlled according to an input sequence of phonetic symbols, following which segmental duration is determined based on the variation of the articulatory parameters. The proposed method is evaluated through an experiment using a Japanese speech database that consists of 150 phonetically balanced sentences. The results indicate that the mean square error of predicted segmental duration is approximately 15[ms] for the closed set and 15-17[ms] for the open set. The error is within 20[ms], the level of acceptability for distortion of segmental duration without loss of naturalness, and hence the method is proved to effectively predict segmental duration.