Prosodic rules for schwa-deletion in hindi text-to-speech synthesis

Abstract

Consonants in written Hindi often carry annotations indicating the nature of the following vowel, which is not written separately. When there is no explicit marking, schwa is the default vowel, but this vowel does not always emerge in a word’s pronunciation. In addition, morphological boundaries can block the deletion of inherent schwas. Previous implementations of schwa deletion in the domain of text-to-speech synthesis (Narasimhan et al., International Journal of Speech Technology, 7(4):319–333, 2004; Choudhury and Basu, Proceedings of the International Conference on Knowledge-Based Computer Systems, 343–353, 2002) delete schwa in phonetic environments that obey the phonotactic constraints of Hindi within word boundaries. Instead of using segmental contexts, in conjunction with a morphological analysis, to predict schwa deletion, we used an account of syllable structure and stress assignment for two- and three-syllable words (Beckman and Pierrehumbert, forthcoming) to predict the presence and absence of schwa in a corpus of phonetically transcribed Hindi. Our algorithm scored as high as 95% accuracy on the deletion of schwa from a small corpus of Hindi words.