Prosody as a marker of information flow in spoken discourse

This study concerns the role of prosody in the structuring of information in monologue discourse, from the point of view of production as well as perception. Two prosodic variables were investigated: speech melody and pauses. Melodically, it was found that local intonation features (falling vs. rising tones) are employed to indicate discourse boundaries. On a more global level, speakers appear to use relative height of pitch peaks and of average pitch values as markers of information units. Furthermore, speakers manipulate both the distribution of pauses and their relative length to mark information flow. A perception experiment was carried out to evaluate the perceptual impact of both speech melody and pauses. It was found that, in the absence of semantic cues, both melodic and pausal information is used by listeners to process the incoming signal in terms of discourse structure.