The Effect of Inspiration and Phonation on Vocal Fold Length

The detection of metric dimensions of laryngeal structures yielded valuable information for both clinical and research purposes. The aim of this paper was to evaluate the absolute dimensions of true vocal fold length (TVFL) during inspiration and phonation with a stroboscope coupling with laser equipment. Forty graduate student subjects including 20 males and 20 females were examined. The measurements were made during inspiration and phonation at a fixed fundamental frequency within each participant. The maximal TVFL was got from the inspiration and the minimal from the phonation. Results showed that the mean values of male inspiration and phonation TVFL were 12.81 + 2.97 mm and 10.92 + 4.40 mm respectively. While in female, they were 11.27 + 2.71 mm and 7.16 + 2.65 mm respectively. There was statistically significant between inspiration and phonation TVFL in the female group. In female, TVFL at phonation was significantly shortened than in male. We concluded stroboscope coupling with laser projection marking module could be used to assess physiological variation of TVFL. This technique enabled the detection of absolute spatial laryngeal dimensions, which was useful in providing valuable information in diagnostics and interpretation of voice disorders.