Date of Award


Document Type

Open Access Thesis


Communication Sciences and Disorders


The Norman J. Arnold School of Public Health

First Advisor

Roozbeh Behroozmand


Speech is a goal-directed movement developed to serve the purpose of human communication. During speech, the brain simultaneously coordinates complex motor behavior and sensory information for planning, execution and online monitoring for error correction in order to ensure accurate delivery of the vocal messages. Models of speech production and voice motor control have adapted the principles of the internal forward model to explain that speech sound production is controlled by comparison of internal predictions with sensory feedback. Growing evidence from studies conducted in speech and limb motor movement indicate that these sensory predictions and responsive commands are loaded in anticipation of voluntary movement. In the present study, we investigated the generation of predictive sensorimotor plans during the planning phase of speech production and the influence of these plans on voice motor control. We hypothesized that the internal forward model is active, and the efference copies are present, during the planning phase of vocal motor movement. Further, we hypothesized that neurophysiological and behavioral mechanisms of vocal motor control are modulated during the planning phase of vocal motor movement. Subjects were instructed to maintain a steady vocalization of a vowel sound and change their voice pitch in upward and downward directions following the onset of a visual cue. During the planning phase of sustained vocalizations, upward and downward pitch-shift stimuli randomly perturbed the speech auditory feedback. Behavioral results revealed compensatory vocal responses and differences in onset latency time and peak magnitude for conditions that loaded a motor plan (i.e., cue up or cue down). Neurophysiological responses revealed direction-specific modulation of P1 responses, N1 suppression for conditions that loaded a motor plan regardless of direction, and modulation of the P2 component only for the upward stimulus direction. These findings contribute to the understanding of the mechanism underlying motor planning during preparation for voice motor control.


© 2016, Stacey Jean Sangtian