Professor Smith's research program focuses on the neurophysiological bases of speech production. She directs a state-of-the-art speech physiology laboratory housed in the department. Her investigations have incorporated a wide variety of physiological measures: electromyography (recordings of electrical activity from orofacial, voice, and respiratory muscles), lung volume and flow analyses, indices of autonomic nervous system activity (skin conductance and pulse volume), and analyses of the complex, 3-dimensional vocal tract movements that occur in speech. Recently a 32 channel EEG system was added to her laboratory, so that the activity of the brain could be recorded during speech and language processing tasks.
Her research has addressed a range of questions, but these questions generally relate to the overall problem of how the brain controls the production of speech. She has worked intensively on the problem of stuttering since 1989, when she began work on a project funded by The National Institutes of Health, "Physiological Correlates of Stuttering." She is currently focusing much of her research effort on the physiological conditions necessary for the forward flow of speech and those that lead to disruptions of speech in stuttering. A number of experiments have been designed to explore interactions between language processing and speech motor performance. She recently expanded her research program to include studies of speech motor development in young children. In 1996, Professor Smith received funding for a five-year project to study speech motor processes in children aged 4- to 16-years.