Date of Award

Fall 2022

Document Type

Open Access Dissertation

Department

Communication Sciences and Disorders

First Advisor

Roozbeh Behroozmand

Abstract

The purpose of this study was to identify behavioral and neural correlates of impaired speech auditory feedback processing in people with a history of left-hemisphere stroke (LHS). To do this, we used the altered auditory feedback (AAF) paradigm to externally induce speech errors by randomly shifting the pitch frequency of the online auditory feedback up or down at ±100 cents in 38 LHS and 27 neurologically intact control participants under two experimental conditions: 1) active vocalizations of a steady speech vowel sound “ah,” and 2) passive listening to the playback of the same self-produced vocalizations. Randomized control trials were included between AAF trials where no pitch-shift stimuli were delivered to the auditory feedback during vocalization or listening tasks. Following each vocalization or listening trial, participants pressed a button to indicate whether they heard a change (i.e., error) in their speech auditory feedback (“Yes” or “No”). Behavioral (i.e., button press responses and vocal motor compensation to AAF) and electroencephalography (EEG) data were collected. Our results revealed decreased perceptual ability for AAF error detection, slowed speech motor compensation responses, and overall decreased magnitude of ERP activity in the LHS group compared with controls, and expression of the speech perturbation response enhancement effect in the N1 ERP component LHS and control groups without between-group differences. There were no significant correlations between the specific behavioral and neurophysiological measures selected in this study. Findings from this research will inform our understanding of sensorimotor processing involved in speech perception, error detection, and motor correction, as well as our knowledge of how impacted brain networks following left-hemisphere injury affect expressive and receptive speech processing which is vital for the spoken communication system. Understanding the impacts and underlying sources of sensory, motor, and/or sensorimotor deficit on speech error detection and correction is important for the development of targeted, efficacious diagnostic and treatment tools to improve communication and quality of life of people with speech disorders.

Rights

© 2022, Stacey Sangtian

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