Dialog speech acts and prosody: considerations for TTS

Abstract

As natural language dialog systems involving both speech recognition and text-to-speech (TTS) synthesis become more sophisticated, the limitations of general-purpose TTS for human-computer dialogs have become more apparent.Much subtlety and complexity of meaning in natural language dialogs is conveyed by prosody; how something is said is often as important as what words are spoken.At the same time, advances such as unit selection synthesis have greatly improved the naturalness of synthetic speech because much less signal processing is required, resulting in less distortion.However, the improved naturalness provided by unit selection synthesis has been achieved at the cost of the more precise prosodic control provided by earlier, more robotic sounding synthesizers.With the goal of providing more prosodic and expressive control over unit selection TTS for dialog applications, while retaining naturalness, we have focused on speech acts, the communicative function of an utterance.The current working set of speech acts being used includes: Imperative: directive