Conscious and unconscious contributions to auditory feedback control of speech — Neural correlates and behavioral consequences

Abstract

AbstractDuring speaking, errors in the auditory feedback are processed rapidly and automatically, suggesting that feedback control of speech operates unconsciously. Yet, humans are also sensitive to consciously detect errors in their auditory feedback during speaking, but research has not probed whether conscious processing of feedback errors modulates speech, or what neural mechanisms underlie conscious detection of errors during speaking. To address these questions, we concurrently measured behavioral vocal responses and electroencephalography (EEG) in 30 participants while their online auditory feedback was altered using individually calibrated threshold-level pitch changes (i.e., errors). Following each vocalization trial, participants reported if they consciously detected pitch errors in their auditory feedback. Our results revealed that irrespective of conscious error detection, participants generated vocal compensation to the altered auditory feedback; however, conscious error detection was associated with increased magnitude of vocal responses roughly 500-700 ms after the altered feedback compared to the unconscious trials. In addition, we found that conscious detection of the altered feedback correlated with early and late neural activity responses as indexed by the modulation of event-related potentials (ERPs). Source localization of ERP responses suggested that conscious error detection was attributed to increased neural activity within the temporal, frontal and parietal cortical networks known to be involved in speech motor control. These findings emphasize the importance of investigating the role of higher-level conscious processing mechanisms in regulating speech feedback control, and their effect on the underlying neural and behavioral functions.