Adult Vocal Fold Length: A Clinical-Anatomical Investigation Using Calibrated Videolaryngoscopy

Vocal folds (VF) are key structures for phonation, and their length varies between individuals depending on sex and anthropometric characteristics. The aim of this study was to measure VF length in healthy adults using videolaryngoscopy and to investigate its relationship with sex, age, height, and weight.

This prospective study was approved by the Ethics Committee of Kayseri City Hospital (September 9, 2025, no: 563). A total of 215 patients (107 males, 108 females; aged 18-88 years) who underwent general anesthesia for various surgical procedures and had no history of laryngeal disease or dysphonia were included. After induction of anesthesia and neuromuscular blockade, videolaryngoscopic images of the glottis were obtained using a HugeMed-VL3R videolaryngoscope (image size 640 × 480 pixels). Calibration of pixel-to-millimeter conversion was performed on three cadaveric larynges by placing a ruler at the level of the VF; 10 mm corresponded to 118 pixels. Intraoperative images were analyzed in ImageJ. Right and left VF lengths were measured at the glottic level by three independent observers, each performing three repeated measurements (nine measurements per VF), and mean values were used for analysis. Statistical analyses were performed using IBM SPSS v23.

The mean age of the participants was 47.1 ± 16.1 years, mean height 167.8 ± 9.1 cm, and mean weight 74.2 ± 14.2 kg. The mean right VF length was 21.95 ± 3.89 mm (range: 10.7-31.5 mm) and the mean left VF length was 22.15 ± 3.92 mm (range: 11.3-31.3 mm). Both right and left VF lengths were significantly longer in males than in females (P < 0.001 for both). Height showed a strong positive correlation with right (r = 0.61, P < 0.001) and left (r = 0.63, P < 0.001) VF length, while weight showed a moderate positive correlation (r ≈ 0.32-0.34, P < 0.001). Age was not significantly correlated with VF length. Multiple regression analysis demonstrated that sex, height, weight, and age together explained 68% of the variance in right VF length and 66% in left VF length.

VF length is strongly associated with sex and height, and to a lesser degree with weight, whereas age has no significant effect on VF length in healthy adults. These findings may provide reference values for laryngeal assessment, preoperative planning, and voice-related clinical decision-making.