ASR and TTS telecommunications applications in Japan

Abstract This paper first describes recent trends of ASR and TTS telecommunications applications in Japan. ASR applications focus on public services such as operator automation, operator assistance, voice-activated information retrieval, and voice dialing. Major TTS applications include information service by voice and e-mail reading. The usage of ASR and TTS functions is expected to dramatically increase in the near future with the penetration of handy and mobile telephone terminals; hot topics are text broadcasting and digital communication. Secondly this paper describes NTT's experimental interactive system featuring (1) highly accurate speaker independent and large vocabulary speech recognition based on context-dependent accurate acoustic phoneme HMM models trained with speech data from more than 10,000 speakers collected over telephone network, (2) high quality text-to-speech synthesis that generates speech by concatenating triphone-context-dependent waveform segments, (3) software-based configuration that requires no special hardware except a PC equipped with a sound board and a voice modem, and (4) easy and rapid prototyping which enables the developer to build a system by writing some types of service scenarios.