On the role of disfluent speech for uncertainty in articulatory speech synthesis

In this paper we present a perception study on the role of disfluent speech in forms of prosodic cues of uncertainty in question-answering situations. In our scenario the answer to each question was modeled by varying three prosodic cues: pause, intonation, and hesitation. The utterances were generated by means of an articulatory speech synthesizer. Subjects were asked to rate each answer on a Likert scale with respect to uncertainty, naturalness and understandability. Results showed evidence for an additive principle of the prosodic cues, i.e. the more cues were activated the higher the perceived level of uncertainty. Overall, the effect of intonation and hesitation was more evident than the effect of pause.