Behroozmand, R., Korzukov, Larson, C.R. ERP
Correlates of Pitch Error Detection in Complex Tone and Voice Auditory Feedback with Missing Fundamental
Brain Research (In Press)
The behavioral evidence from previous studies has shown that the pitch of a periodic complex sound is perceived in the absence of its fundamental frequency (F0). This effect suggests that a distinct neural processing mechanism may resolve pitch based on a pattern that exists between harmonic frequencies of auditory stimuli. The present study investigated whether such a mechanism is active during voice pitch control. Event-related potentials (ERPs) were recorded in response to +200 cents pitch shifts in the auditory feedback of self-produced vocalizations and periodic complex tones with and without the F0. The absence of the fundamental induced no difference in ERP latencies compared to when it was present in voice or complex tones feedback. However, a right-hemisphere difference was found in the N1 amplitudes with significantly larger responses to complex tones that included the fundamental compared to when it was missing. In addition, the P1 and N1 latencies were shorter in the left hemisphere, and the amplitudes of the N1 and P2 were larger bilaterally for pitch shifts in voice and complex tones (with and without the F0) compared with pure tones feedback. These findings suggest hemispheric differences in neural encoding of pitch in complex sounds with missing fundamental. Results of previous studies suggest the left and right hemispheres differentially use spectral and temporal cues for pitch encoding. Data from the present study suggest that the right cortical auditory areas, thought to be specialized for spectral processing, may utilize different neural mechanisms to resolve pitch in sounds with and without the fundamental. Moreover, the left hemisphere seems to perform faster neural processing in order to resolve pitch based on the rate of temporal variations in complex sounds compared with pure tones. These effects indicate that the differential neural processing of pitch in the left and right hemispheres may enable the audio-vocal system to detect temporal and spectral variations in the auditory feedback for vocal motor control during speaking.