Vocal pitch enables differential motor learning of speech segments.

Abstract

Sensory feedback is crucial for accurate motor control. One process of movement correction is sensorimotor adaptation, or motor learning in response to perceived sensory errors. Recent studies demonstrate that people can adapt to opposing errors on a single movement given a context that differentiates when each error occurs. In speech production, linguistic structure (e.g., the same vowel in different words) can provide context for differential adaptation, but it is unclear whether this is restricted to the same effectors (i.e., lips, tongue, jaw) or also includes movements of other speech effectors (i.e., the larynx). Reaching studies show that contextual movements need not be produced with the same effector as the learning target, but so far, they have only tested left-right pairs. We present three simultaneous adaptation experiments in speech that examine whether laryngeal movements for pitch can provide context for oral articulator movements for vowels. In each experiment, the resonances that correlate with vowel articulator position were perturbed in three directions that were predictable given a pitch context. First, Mandarin speakers differentially adapted given pitch contexts that signal differences in word meaning, suggesting that lexical pitch provides context for vowels. Second, English speakers differentially adapted given arbitrary pitch matching contexts on the word "head," suggesting that nonmeaningful pitch movements provide context for vowels. Third, English speakers did not differentially adapt when listening to contextual pitch, indicating that mere auditory input of pitch is insufficient. Together, these results suggest that sensorimotor context for learning can be provided by effectors other than the learning target.NEW & NOTEWORTHY Previous work shows that sensorimotor learning can be specific to different motor contexts, but to date, this research has only examined contexts provided by the same effector as the learning target or its contralateral pair. We show that laryngeal movements for pitch enable differentiated learning of oral articulator movements for vowels, even when the pitch is linguistically meaningless. This indicates that motor contexts that enable learning can be generated by effectors distinct from those that undergo learning.