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Free keywords:
speech production
speech perception
auditory feedback
MEG
Abstract:
An important aspect of L2 speech learning is the interaction between speech production and perception. One way to study this interaction is to provide speakers with altered auditory feedback to investigate how unexpected auditory feedback affects subsequent speech production. Although it is generally well established that speakers on average compensate for auditory feedback perturbations, even when unaware of the manipulation, the neural correlates of responses to perturbed auditory feedback are not well understood. In the present study, we provided speakers with auditory feedback that was intermittently pitch-shifted, while we measured the speaker’s neural activity using magneto-encephalography (MEG). Participants were instructed to vocalize the Dutch vowel /e/ while they tried to match the pitch of a short tone. During vocalization, participants received auditory feedback through headphones. In half of the trials, the pitch in the feedback signal was shifted by -25 cents, starting at a jittered delay after speech onset and lasting for 500ms. Trials with perturbed feedback and control trials (with normal feedback) were in random order. Post-experiment questionnaires showed that none of the participants was aware of the pitch manipulation. Behaviorally, the results show that participants on average compensated for the auditory feedback by shifting the pitch of their speech in the opposite (upward) direction. This suggests that even though participants were not aware of the pitch shift, they automatically compensate for the unexpected feedback signal. The MEG results show a right-lateralized response to both onset and offset of the pitch perturbation during speaking. We suggest this response relates to detection of the mismatch between the predicted and perceived feedback signals, which could subsequently drive behavioral adjustments. These results are in line with recent models of speech motor control and provide further insights into the neural correlates of speech production and speech feedback processing.
