The Length Measurement and Strain Calculation of Vocal Folds in Young Opera Singers with Different Voice...

This study aims to investigate the utility of real-time ultrasound in the length measurement and strain calculation of the vocal folds among young professional singers with diverse vocal classifications.

A total of 102 young singers, including 31 sopranos, 23 mezzo-sopranos, 27 tenors, and 21 baritones, were enrolled in this study. The glottis of each subject was scanned using real-time ultrasound imaging during breath-holding tests and while singing "e" at a low pitch, medium pitch, and high pitch. The image quality of the vocal folds was graded, and the vocal folds length (VFL) of each singer was measured. Multiple photos of each measurement were taken, using both "excellent" and "good" quality images. Strain, the ratio of elongated or shortened vocal folds during singing to their initial length during breath holding was calculated for all pitches. The parameters were compared among groups to explore potential associations with different vocal classifications.

The image quality exhibited a declining trend from breath-holding to singing the high pitch, with two cases (2%) being classified as poor. As the pitch increased, both male and female singers had an elevation in the VFL and strain. Female, mezzo-sopranos demonstrated significantly longer vocal folds than sopranos in each state, while the strain was comparable between the two groups. Male, baritones consistently exhibited longer vocal folds in every state; however, no statistically significant differences were observed during breath-holding and singing high tones. Baritones also exhibited higher strains, with significant differences observed for both low and medium pitches, whereas no significant difference was found for high pitches.

Real-time ultrasound can be used as a noninvasive tool for length measurement of vocal folds among singers with different singing voices.