Development of Assamese Text-to-speech synthesis system

This paper presents the design and development of Assamese Text to speech (TTS) synthesis system. In particular, work focused on designing language specific rules, developing quality database, data segmentation, and to handle bilingual sound units. In Assamese language, till now no study is done to construct the grapheme to phoneme conversion rules. In this work, grapheme to phoneme conversion rules are proposed for Assamese language. The database is recorded by checking the speaking rate, variation in amplitude level, dc wandering, and clipping during data collection. A significant improvement in the synthesized voice is observed by ensuring uniform speaking rate, controlling variation in the signal amplitude level, and avoiding dc wandering and clipping during data collection. A semi-automatic segmentation approach is developed for data segmentation. Initially, segmentation is done by automatic process and later manual correction of segmentation boundaries is done to improve quality and intelligibility. It also reduce time required for the segmentation process. The developed TTS can work in bilingual mode. It can switch between Assamese and English language smoothly and maintains the sentence level intonation even for mixed texts.