Speech recognition and synthesis technology development at NTT for telecommunications services

This paper describes recent developments at NTT in the areas of speech recognition, speech synthesis, and interactive voice systems as they relate to telecommunications applications. Speaker-independent largevocabulary speech recognition based on context-dependent phone models and LR parser, and high-quality text-to-speech (TTS) conversion using the waveform concatenation method, both realized as software, have enabled interactive voice systems for fast and easy prototyping of telephone-based applications. Practical applications are discussed with examples.