The purpose of this study was to examine external laryngeal oscillation and its potential effects on phonation threshold pressure (PTP; cm H2O) and phonation threshold flow (PTF; L/sec). Measures of PTP and PTF have inherent limitations due to the nonlinear nature of phonation, influencing their clinical and experimental utility. This is true particularly for tracking relatively small changes in voice function because variability in the measure itself can be larger than that resulting from voice change. Elevated PTP and PTF are associated with a variety of voice disorders and correlate with self-reported vocal effort and fatigue. Prior studies involving silicone and excised animal larynges have demonstrated PTP reduction in response to external oscillation. In an extension of this work, this thesis examined external laryngeal oscillation and aerodynamic voice measures in two experiments including a translational benchtop to human approach. Experiment 1 used a within-subjects counterbalanced design to examine PTF in 12 porcine larynges. Larynges were fitted with a custom oscillation device and 30 phonation trials were conducted for each larynx, 15 with external oscillation and 15 without. Although summary statistics indicated that PTF was lower with external oscillation, differences were not significant. Experiment 2 applied a within-subjects counterbalanced design to examine PTP in four healthy adult females and one healthy adult male. Individuals produced repeated syllable strings of /pi/ productions at comfortable pitch with and without external oscillation using an electrolarynx and the second and third syllables were averaged. Descriptive analysis indicated that PTP was lowered for female participants but not the male participant. Taken together, the results of these studies offer preliminary evidence that external oscillation influences voice onset aerodynamic measures. The effects of external oscillation seem to be more evident in PTP. These findings have important clinical and research applications for PTP measurement and the potential positive influence on voice function. These preliminary results indicate the need for further research in this area.



College and Department

David O. McKay School of Education; Communication Disorders



Date Submitted


Document Type





phonation threshold pressure, phonation threshold flow, benchtop model, excised larynx, laryngeal oscillation



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