Effects of Surface Dehydration on Mucosal Wave Amplitude and Frequency in Excised Canine Larynges

Abstract

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 eight excised canine larynges during exposure to dehumidified air at 20 cm H2O. Control trials consisted of high-speed videos recorded for two 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=0.003) as well as the percent change (p<0.001) 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<0.001; p=0.027). 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.

Quantitative Study for the Surface Dehydration of Vocal Folds Based on High-Speed Imaging

“…Although previous research has revealed that the fundamental frequency significantly decreased in dehydrated larynges, 15 there was no significant difference in this study. Dehydration was able to cause muscle contraction, which could result in a larger glottal gap.…”

Climate, vocal folds, and tonal languages: Connecting the physiological and geographic dots

“…These deleterious effects of desiccated air on precise phonation have also been confirmed in a series of ex vivo studies with excised canine and ovine larynges (31)(32)(33). This confirmation suggests plainly that the sensitivity of speakers' vocal cords to desiccated air is genotypically and phenotypically normal and operative across all human populations.…”

Connections Between Voice Ergonomic Risk Factors and Voice Symptoms, Voice Handicap, and Respiratory Tract Diseases

“…It stiffens the cover of vocal folds and increases the viscosity of mucosa, 36 which, in turn, changes the mucosal wave by decreasing its amplitude and frequency. 37,38 As a result, the phonation threshold pressure increases. [39][40][41][42] Some voice ergonomic risk factors, like working posture and emotions, are related to the speaker.…”