Probing effects of lexical prosody on speech-gesture integration in prominence production by Swedish news presenters

This study investigates the multimodal implementation of prosodic-phonological categories, asking whether the accentual fall and the following rise in the Swedish word accents (Accent 1, Accent 2) are varied as a function of accompanying head and eyebrow gestures. Our purpose is to evaluate the hypothesis that prominence production displays a cumulative relation between acoustic and kinematic dimensions of spoken language, especially focusing on the clustering of gestures (head, eyebrows), at the same time asking if lexical-prosodic features would interfere with this cumulative relation. Our materials comprise 12 minutes of speech from Swedish television news presentations. The results reveal a significant trend for larger fo rises when a head movement accompanies the accented word, and even larger when an additional eyebrow movement is present. This trend is observed for accentual rises that encode phrase-level prominence, but not for accentual falls that are primarily related to lexical prosody. Moreover, the trend is manifested differently in different lexical-prosodic categories (Accent 1 versus Accent 2 with one versus two lexical stresses). The study provides novel support for a cumulative-cue hypothesis and the assumption that prominence production is essentially multimodal, well in line with the idea of speech and gesture as an integrated system.