Coupling among speakers during synchronous speaking in English and Mandarin

The laboratory task of synchronous speech is considered as an experimental analog of the ubiquitous phenomenon of choral speaking. We here consider some implications that arise if we regard two synchronous speakers as mutually entrained systems. Firstly, the degree of synchrony should be a function of the strength of coupling between speakers. Secondly, the entrainment would necessarily be vulnerable to perturbation. We test both these predictions, first in English and then in Mandarin Chinese. We demonstrate that modulation of the auditory link between speakers strongly affects synchronization in both languages. We also find that mismatched texts are an effective way of inducing speech errors in English, but not in Mandarin. The errors found in English frequently involve the complete breakdown of the act of speaking. An unexpected finding is that Mandarin may be pronounced with a distinct syllabic regularity in the synchronous condition. A post hoc analysis attests that the syllable is more regularly timed in synchronous Mandarin than when spoken by one person, but this effect is absent in English. We hypothesize that the strongly articulated syllable provides synchronous Mandarin with a stability in the face of perturbation.