A set of corpus-based text-to-speech synthesis technologies for Mandarin Chinese

This paper presents a set of corpus-based text-to-speech synthesis technologies for Mandarin Chinese. A large speech corpus produced by a single speaker is used, and the speech output is synthesized from waveform units of variable lengths, with desired linguistic properties, retrieved from this corpus. Detailed methodologies were developed for designing “phonetically rich” and “prosodically rich” corpora by automatically selecting sentences from a large text corpus to include as many desired phonetic combinations and prosodic features as possible. Automatic phonetic labeling with iterative correction rules and automatic prosodic labeling with a multi-pass top-down procedure were also developed such that the labeling process for the corpora can be completely automatic. Hierarchical prosodic structure for an arbitrary desired text sentence is then generated based on the identification of different levels of break indices, and the prosodic feature sets and appropriate waveform units are finally selected and retrieved from the corpus, modified if necessary, and concatenated to produce the output speech. The special structure of Mandarin Chinese has been carefully considered in all these technologies, and preliminary assessments indicated very encouraging synthesized speech quality.