Coverbal speech gestures signal phrase boundaries: A production study of Japanese and English infant- and adult-directed speech

International audienceThe acoustic realization of phrasal prominence is proposed to correlate with the order of V(erbs) and O(bjects) in natural languages. The present production study with 15 talkers of Japanese (OV) and English (VO) investigates whether the speech signal contains coverbal visual information that covaries with auditory prosody, in Infant- and Adult-Directed Speech (IDS and ADS). Acoustic analysis revealed that phrasal prominence is carried bydifferent acoustic cues in the two languages and speech styles, while analyses of motion showed that this acoustic prominence is not accompaniedby coverbal gestures. Instead, the talkers of both languages produced eyebrow movements to mark the boundaries of target phrases withinelicited utterances in combination with head nods. These results suggest that the signal might contain multimodal information to phrase boundaries,which could help listeners chunk phrases from the input