Word intelligibility testing and TTS system improvement

An approach of word intelligibility evaluation and diagnose of an embedded English TTS system for improvement is presented. The TTS engine is based on the concatenation of variable-length speech units. Multi-Syllable Word Test (MSWT) word corpus is designed for the evaluation. Letter to sound, syllable boundary, prosodie satisfactory, concatenation smoothness, compression distortion as well as the isolated word intelligibility as a whole is tested. Diagnostic analysis cycle is conducted to give the guideline of improving the system. Testing strategy, testing material design, testing tool design and testing procedure are described. Discussion is given. The approach can be applied to different languages and can be adopted for filternate TTS approaches such as HTS.