Objective: Evaluate the effect of vocal fold surface dehydration on mucosal wave amplitude and frequency.
Study design: Controlled test-retest.
Setting: Larynges were mounted on an excised larynx phonation system and attached to a pseudolung in a triple-walled sound-attenuated room that eliminated background noise and maintained a stabilized room temperature and humidity level.
Subjects and methods: High-speed video was recorded for 8 excised canine larynges during exposure to dehumidified air at 20 cm H(2)O. Control trials consisted of high-speed videos recorded for 2 excised canine larynges during exposure to humidified air at the same pressure.
Results: In the majority of larynges, increased levels of dehydration were correlated with decreased amplitude and frequency. The slope of the linear regression fitted to the change in amplitude (P = .003) and the percent change (P < .001) between the initial and final trials were significantly decreased in dehydrated larynges. These measurements with respect to the change in frequency were also significantly decreased in dehydrated larynges (P < .001; P = .027).
Conclusion: Vocal fold surface dehydration caused a decrease in mucosal wave amplitude and frequency. This study provides objective, quantitative support for the mechanism of voice deterioration observed after extreme surface dehydration.