The timing of head nods is constrained by prosodic structure

Abstract

Purpose: previous studies in the field of prosody-gesture alignment have found that/nprominent parts of gestures are temporally aligned with prosodically prominent parts of /nthe utterance. Yet, little is known about the precise alignment of gestures with respect to /nthe prosodic structure of the associated speech. Hypotheses: in confirmation utterances (a) the position of the nuclear accented syllable with respect to an upcoming prosodic boundary influences the timing of the intensity peak within that syllable, (b) the position of the nuclear accented syllable with respect to an upcoming prosodic boundary influences the timing of the associated head nod gesture, and (c) the apex of the head nod gesture is temporally aligned with the intensity peak of the nuclear accented syllable. Method: 11 Catalan speakers performed a Discourse Completion Task involving confirmatory contexts. /nRecordings of spontaneously occurring co-speech head nod gestures were acoustically and gesturally analyzed. Results: head nod apexes and intensity peaks are temporally associated with the end of the accented syllable in words with penultimate and antepenultimate stress, while they are temporally retracted in monosyllables and iambs when immediately preceding a prosodic boundary. Conclusions: these results expand the findings by Esteve-Gibert & Prieto (2013), showing that the timing of gesture apexes in head nod gestures produced in semi-spontaneous speech is conditioned by the proximity to prosodic boundaries, as well as by the metrical structure of the prominent word in the utterance. Moreover, this study shows that in addition to the intonational peak of the nuclear accented syllable, its intensity peak also highly correlates with the gesture apex.