Year of Publication

2016

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Health Sciences

Department

Rehabilitation Sciences

First Advisor

Dr. Joseph Stemple

Abstract

Healthy voicing is thought to be dependent on a dynamic balance of three interactive subsystems: respiration, phonation, and resonance. Theoretically, multiple patterns of subsystem interactions likely underlie healthy voice production; however surprisingly little quantitative data exists defining the nature of these subsystem production patterns and interactions across individuals.

The central aim of this study was to quantify the interactions of the vocalization subsystems in a non-perturbed and perturbed condition (induced unilateral vocal fold paralysis) in 10 vocally healthy participants. Respiratory inductance plethysmography, laryngeal aerodynamics, and acoustic formant data were used to measure the proportional contributions of, and changes to, the three vocal subsystems during voice production tasks. The overall hypothesis was that individuals would demonstrate distinctive patterns of change in voice subsystem interaction across vocalization conditions, resulting in characteristic vocalization profiles.

Using Dynamics Systems Theory (DST) as a guide, we hypothesized that analysis of group data alone would hide important individual variability that would help better understand differences in subsystem regulation across individuals. Additionally, in accordance with DST, we hypothesized that although there would be individual variability during voice production tasks, only a small group of characteristic subsystem patterns would emerge, permitting subgrouping of individuals into unique vocalization profiles.

Results demonstrated that group data masked important aspects of individual performance. Despite all individuals demonstrating paramedian paralysis on visualization during the perturbation phase, unique subsystem patterning strategies for coping with the acute vocal fold paralysis were observed. Despite individual variability, subgroups were able to be determined which revealed commonalities in the dominant physiologic strategies of subsystem regulation across individuals. A dynamic systems state space model was constructed as a visual aid to demonstrate that the changes noted between voicing conditions were not random, but rather formed specific trajectories. Implications for translation of these results into clinical practice are discussed.

Digital Object Identifier (DOI)

https://doi.org/10.13023/ETD.2017.007

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