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. In particular, we ask whether the realization of the accentual fall (HL) and the following so-called big-accent rise (H) in the Swedish word accents (Accent 1, Accent 2) is varied as a function of accompanying head and eyebrow gestures. The purpose of this study is to evaluate the hypothesis that prominence production displays a cumulative relation between the acoustic and the kinematic dimensions of spoken language, especially focusing on the clustering of different types of gestures (head, eyebrows), at the same time asking if lexical-prosodic features would interfere with this cumulative relation. The material tested are 60 brief news readings from Swedish television, comprising about 12 minutes of speech from five news presenters (two female). The results reveal a significant trend for larger fo rises (in semitones) 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 (words with Accent 1 vs. Accent 2, and with one vs. 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.