Slide Slam G2
Synchronised speech and speech motor control: convergence in voice fundamental frequency during choral speech
Abigail R. Bradshaw1, Carolyn McGettigan1; 1University College London
Synchronised speech behaviours such as choral speech (speaking in unison) are found in a variety of everyday settings, and have clinical relevance as a temporary fluency-enhancing technique for people who stutter. It is currently unknown whether such synchronisation of speech timing among two speakers is also accompanied by alignment in their vocal characteristics, for example in acoustic measures such as pitch. The current study investigated this by testing whether convergence in voice fundamental frequency (F0) between speakers could be demonstrated during choral speech. Sixty participants across three online experiments were audio recorded whilst reading a series of sentences, first on their own, and then in synchrony with another speaker (the accompanist) in a number of between-subject conditions. Experiment 1 demonstrated significant convergence in participants’ F0 to a pre-recorded accompanist voice, in the form of both upward (high F0 accompanist condition) and downward (low F0 accompanist condition) changes in F0; however, upward convergence was greater than downward convergence. Experiment 2 found that downward convergent changes in F0 could not be increased by the use of an accompanist voice with an even lower F0. Experiment 3 demonstrated that such convergence was not seen during a visual choral speech condition, in which participants spoke in synchrony with silent video recordings of the accompanist. Further, convergence in F0 was enhanced for a condition where participants could both see and hear the accompanist in pre-recorded videos compared to synchronisation with the pre-recorded voice alone. These findings suggest the need for models of speech motor control to incorporate interactions between self- and other-speech feedback during speech production, and suggest a novel hypothesis for the mechanisms underlying the fluency-enhancing effects of choral speech in people who stutter.