Motor and sensory adaptation following auditory perturbation of /s/ production

Abstract

Studies of motor adaptation have provided valuable insights into the role of auditory and orosensory feedback in speech production. While perturbations to the structure of the vocal tract (e.g., pseudopalate), which alter both orosensory and auditory feedback, have been used to investigate the production of a range of consonants and vowels, studies of short-term speech adaptation utilizing purely auditory feedback manipulations (e.g., spectral shifting) have been mostly limited to investigations of vowel production. These studies have revealed that motor plans underlying vowel production are flexible, and that subjects will readily alter their motor output in order to achieve auditory perceptual targets. In the present study, we have extended this work by spectrally shifting the acoustic signal for the sibilant /s/ during the production of short /s/-initial words. Evidence of motor adaptation was observed following a brief, intensive period of practice under altered auditory conditions, indicating a role for auditory feedback in sibilant production. In addition to changes in speech motor output, subjects showed changes to their auditory-sensory representations of /s/ and /∫/ following the manipulation, suggesting that adaptation was not limited to the motor domain. These results will be discussed in the context of current models of speech motor control.