Functional neural oscillatory activities reveal the impact of attentional instructions on speech auditory feedback...

Speech production relies on precise integrations between vocal and auditory feedback mechanisms for fluent verbal communication. This study investigated how explicit attentional instructions influence speech auditory feedback control. A total of forty-three participants performed speech vowel vocalizations while receiving brief (200 ms) and randomized pitch shifts at ±100 cents magnitude in their auditory feedback during concurrent electroencephalography (EEG) recordings. Twenty-one participants were randomly assigned to an attentional-instruction group and were instructed to focus their attention on detecting pitch-shift stimuli via pressing a button whereas no such instructions were provided for the remaining twenty-two participants in the no-instruction group. Behavioral data revealed a significantly smaller peak magnitude of vocal compensation responses to auditory feedback alterations in the attentional-instruction compared with no-instruction group, suggesting an attentional modulation of the speech motor control mechanisms. Time-frequency analyses of EEG data showed a significantly stronger desynchronization of the high-beta band (20-30 Hz) neural activities for the attentional-instruction group, indicating enhanced audio-vocal integration when participants attentively monitored their speech feedback. In addition, we found that the accuracy of button-press responses for detecting pitch shifts positively correlated with the alpha and beta band power (8-30 Hz) while compensation magnitude positively correlated only with the gamma band power (30-80 Hz). These findings provide new insights into the effects of attentional instruction on the neural and behavioral correlates of speech motor control, emphasizing its application as a viable tool for targeted treatment of speech disorders in clinical populations.