Sensorimotor coupling underlies individual differences in speech synchronization

Abstract

Behavioral auditory–motor interaction in speech reveals a striking individual difference: while some individuals readily synchronize their produced syllabic rhythm with the perceived one (high synchronizers), others show impaired synchronization (low synchronizers). The mechanisms underlying this distinction remain debated. One account attributes it to differences in the strength of sensorimotor coupling, whereas an alternative proposes differences in the relative contributions of feedback and feedforward control. Here, using an online protocol, we evaluated participants with an adapted version of the Battery for the Assessment of Auditory Sensorimotor and Timing Abilities (BAASTA) and found that high synchronizers exhibit both stronger synchronization during paced tapping tasks and greater rhythmic stability during unpaced tapping tasks. Crucially, we adapted a biophysical model in which motor behavior is represented as an oscillator coupled to sensory input, and simulated individuals as differing in coupling strength. The simulations closely match the empirical observations, demonstrating that stronger sensorimotor coupling is sufficient to reproduce the observed differences in speech synchronization.