The Influence of Tone on the Alignment of Speech and Co-Speech Gesture

Evidence continues to accrue suggesting that co-speech gestures form an integrated part of the prosodic system of languages. Several studies have highlighted a tight link between the timing of gestures of the hands and head with syllables bearing prosodic prominence. Most work to date has examined this relationship in Indo-European languages, where gestures appear to be crucially timed with respect to pitch-accented syllables. Less work has examined the timing of co-speech gestures in tonal languages, where pitch plays quite a different role within the phonological system. Here, we examine the influence of tone on the timing of manual co-speech gestures in Medmba, a Grassfields Bantu language spoken in Cameroon. We investigate 1) whether certain tones are more likely than others to associate with manual gestures in the language; and 2) whether the fine timing of the speech-gesture relationship is influenced by the tone or relative fundamental frequency ( f 0 ) of the syllable it co-occurs with. Our findings indicated no preference for any one tone to occur with co-speech gestures. However, gesture apexes were found to align significantly later with respect to the accompanying syllable’s vowel for low-toned syllables as compared with syllables of other tones.