Establishment and Analysis of False Vocal Folds Hypertrophy Model in Excised Canine Larynges.

Abstract

OBJECTIVE: This study aimed to investigate the role of false vocal folds (FVFs) medialization in phonation and the acoustic impact of ventricular hypertrophy by establishing an FVF hypertrophy model. STUDY DESIGN: A prospective in vitro experiment was carried out. SETTING: The study was carried out using a pseudolung platform with high-speed camera in a soundproof room. MATERIALS AND METHODS: Control, degree I, and degree II FVFs hypertrophy were simulated in 10 excised larynges via fructose injection of 0.1&#x2009;mL for degree I and 0.25&#x2009;mL for degree II. Mean flow rate (MFR), fundamental frequencies (F0), formants, and sound pressure level were measured with a subglottal pressure of 1.5&#x2009;kPa and 2.5&#x2009;kPa, respectively. RESULTS: When the subglottal pressure was controlled at both at 1.5&#x2009;kPa and at 2.5&#x2009;kPa, the degree of FVF hypertrophy significantly influenced the distribution of the formants, F0, and MFR in excised canine larynges. Increasing the degree of hypertrophy was associated with a decrease in F0 and an increase in MFR. In degree II FVF hypertrophy models, the sound pressure level and the first formant were significantly higher (P&#x2009;<&#x2009;0.05) than in normal models. CONCLUSION: Hypertrophy of the FVFs has a significant influence on the distribution of sound energy and is associated with changes in sound quality.