Date of Award

8-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Speech, Language, and Hearing Sciences

First Advisor

Preeti M. Sivasankar

Committee Chair

Preeti M. Sivasankar

Committee Member 1

Stacey Halum

Committee Member 2

Anne Smith

Committee Member 3

Susan deCrane

Abstract

Vocal loading adversely affects the healthy larynx. The negative effects of vocal loading are thought to be exacerbated in dry environments, noisy environments, using non-habitual speaking patterns, and voice quality. Advancing age is also thought to be a risk factor for the negative effects of loading. To systematically tease out the effects of these factors on the healthy larynx, three different experiments were conducted. In each experiment, healthy participants produced 45-minutes of child-directed speech. In experiment 1, older, healthy adults produced loud child-directed speech, in the presence of background noise, in both low and moderate humidities, and voice was assessed. In experiment 2, young, healthy adults produced loud child-directed speech, in the presence of background noise, in both low and moderate humidities, and voice was assessed. In experiment 3, young, healthy adults produced child-directed speech using low-effort whisper quality and voice was assessed. In each experiment, voice measures included Phonation Threshold Pressure, Cepstral Peak Prominence, self-perceived phonatory effort, and self-perceived vocal tiredness. These voice measures were collected at set points of the frequency range. Our data suggest that the aging larynx is negatively affected by 45-minutes of loud child-directed speech and that humidification is beneficial in reducing these negative effects. Younger adults are also negatively affected by 45- minutes of loud child-directed speech, but not whispered speech. Increasing ambient humidity does not minimize these effects. The adverse effects of loud speech are much greater than whispered speech. Overall, these data increase our understanding of factors that load the larynx and lay the foundation for developing clinical tests to identify speakers who are susceptible to voice problems.

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