Towards Expressive Speech Synthesis in English on a Robotic Platform

Affect influences speech, not only in the words we choose, but in the way we say them. This paper reviews the research on vocal correlates in the expression of affect and examines the ability of currently available major text-to-speech (TTS) systems to synthesize expressive speech for an emotional robot guide. Speech features discussed include pitch, duration, loudness, spectral structure, and voice quality. TTS systems are examined as to their ability to control the features needed for synthesizing expressive speech: pitch, duration, loudness, and voice quality. The OpenMARY system is recommended since it provides the highest amount of control over speech production as well as the ability to work with a sophisticated intonation model. OpenMARY is being actively developed, is supported on our current Linux platform, and provides timing information for talking heads such as our current robot face.