Prosodic encoding in Mandarin spontaneous speech: Evidence for clause-based advanced planning in language production

This study reports the cross-boundary f0 shifting of prosodic units (PU) in Mandarin conversational speech by analyzing the PU-initial and PU-final f0 heights as a function of its semantic structure. Initial and final f0 heights were defined as the f0 values extracted at the energy max of the first and the last syllable of the PU. The semantic structure of the PU was defined based on its co-extensiveness with a semantic unit in discourse (DU), i.e., a proposition, often encoded by a clause. Our analysis shows significant relationships between the cross-boundary f0 heights and the PU-DU co-extensiveness. PU-DU left alignment introduces a significant up-shifting effect on both initial and final f0 heights. This pitch resetting is effective across the whole PU, suggesting speakers’ sensitivity to the initiation of propositions in production. On the other hand, PU-DU right alignment introduces a down-shifting effect on both f0 heights. The regressive f0-lowering observed in the PU-initial f0 heights (anticipatory effect based on the PU-terminal semantics) and the progressive f0-raising of the PU-final f0 heights (carried-over effect based on the PU-initial semantics) both shed light on the psycholinguistic importance of the proposition and support its central role in advanced planning in spontaneous speech production.