There has been a wealth of research investigating semi-occluded vocal tract exercises (SOVTs) from a theoretical perspective. The physiologic mechanisms underlying these popular voice rehabilitation and training exercises have been studied primarily through modelling studies and non-functional imaging studies (e.g. CT/MRI). More functional research, analyzing acoustic, aerodynamic, EGG, EMG, endoscopic, auditory-perceptual, and self-perceptual effects of SOVTs, have produced variable results. The primary goal of this dissertation was to address the variability of these results and fill in gaps in the literature through four experiments. Experiment 1 sought to identify trends in the prescription practices of SOVTs across speech-language pathologists using a web-based survey. Experiments 2 and 3 aimed to assess the immediate acoustic, auditory-perceptual, and self-perceptual effects of two SOVT exercises (straw phonation and straw phonation into a cup of water) delivered remotely through telepractice. Experiment 4’s objective was to explore the physiologic vocal fold vibratory characteristics that occur during SOVT production, using high-speed videoendoscopy (HSV). Results revealed that clinicians are very knowledgeable about underlying physiology of SOVTs, despite not feeling prepared to prescribe them following their graduate programs. Other interesting findings regarding the effect of clinician experience level on the types of SOVTs being prescribed will be discussed. Acoustically, a statistically significant decrease in shimmer (p=.016) was noted followingstraw phonation. Auditory-perceptual analysis, performed by three experienced SLP raters, revealed a statistically significant increase (p=.009) in the perception of strain following straw phonation into a cup of water. While no significant differences were found between SOVT tasks in self-perception of vocal effort, a statistically significant increase (p=.006) in self-perception of vocal loudness was reported following straw phonation into a cup of water. Descriptive analysis of HSV revealed increases in glottal attack time and glottal offset time following SOVTs. Glottal contact closed quotient provided mixed results. Future research should continue to advance functional outcomes of SOVTs including the study of the underlying physiology using innovative methods such as HSV.
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