Age-related and anthropometric aspects of voice mutation in adolescents: An observational single-center cohort study

Background. The time of onset of voice mutation in adolescent boys varies among different peoples and depends on their weight, as well as genetic, geographic, and socioeconomic conditions. Boys from the South experience voice mutation at the ages of 12–13 years, while in boys from the North, it begins at the ages of 14–15 years. Although Irkutsk belongs to the southern regions of Eastern Siberia (lying in the same latitude as Saratov and Orenburg), in terms of its sharply continental climate, it is similar to the northern regions. The lack of data on the onset of voice mutation in Siberian adolescents, the effect of excess weight on its onset, the relationship between the vocal fold length and other anthropometric measures during puberty, and the possibility of an accurate measurement of the vocal fold length in adolescents prompted the present study. Objective. To determine the age of voice mutation onset in Irkutsk adolescents; vocal fold length and thyroid cartilage angle prior to, during, and after mutation, as well as the relationship between these parameters and weight, height, foot length, and neck circumference. Methods. An observational single-center cohort study was conducted by the specialists of the Otolaryngology Department of the Irkutsk State Medical University in March–May 2024; the study included 77 boys and 70 girls (6th–8th graders from two Irkutsk schools), whose vocal fold length and thyroid cartilage angle were measured via laryngeal ultrasound by means of a ChisonSonoEye P2 ultrasound machine (Chison, China) with a 10 MHz linear probe. The boys’ voices were evaluated by ear by a panel of three otolaryngologists, after which they were divided into groups according to the stage of voice mutation: pre-mutation (n = 29), mutation (n = 24), and post-mutation (n = 24). The age of voice mutation onset was determined; height, weight, neck circumference, and foot length were measured, and body mass index was calculated. For a comparative analysis of these measures in boys and girls, all study participants were distributed by age without taking voice changes into account: Group 1A comprising adolescent boys aged 12 years (n = 20); Group 2A comprising adolescent boys aged 13 years (n = 30); Group 3A comprising adolescent boys aged 14 years (n = 27); Group 1B comprising adolescent girls aged 12 years (n = 16); Group 2B comprising adolescent girls aged 13 years (n = 15); Group 3B comprising adolescent girls aged 14 years (n = 39). Statistical processing of data was performed using Statistica 10.0 (StatSoft, Tulsa, USA). Differences were considered to be statistically significant at an error level of p < 0.05. Results. Irkutsk boys were found to experience voice mutation at the ages of 12–13 years, with the vocal fold length exceeding 2 cm. Significant correlation coefficients were found between vocal fold length in adolescent boys and age (r = 0.66, p = 0.03), weight (r = 0.53, p = 0.04), height (r = 0.68, p = 0.02), foot length (r = 0.63, p = 0.04), neck circumference (r = 0.39, p = 0.03), body mass index (r = 0.28, p = 0.04), and thyroid cartilage angle (r = −0.43, p = 0.04); in adolescent girls, between vocal fold length and age (r = 0.59, p = 0.04), weight (r = 0.37, p = 0.02), and body mass index (r = 0.32, p = 0.04). At the age of 14 years, the girls’ vocal folds measured 20.1 ± 2.1 mm, i.e., were significantly longer (p = 0.001) than at 12 (17.2 ± 1.8 mm) and 13 years of age (17.7 ± 1.9 mm). At the age of 12 years, the boys had a smaller thyroid cartilage angle (94.2 ± 9.4°, p = 0.036) than the girls (105.1 ± 8.6°). From the age of 13 years, adolescents of both sexes already differed in vocal fold length (19.3 ± 2.6 mm in boys and 17.7 ± 1.9 mm in girls, p = 0.049), foot length (26.2 ± 2.3 and 23.7 ± 1.2 cm, respectively, p = 0.001), and neck circumference (31.6 ± 2.8 and 28.9 ± 1.1 cm, p = 0.001); from the age of 14 years, also in weight (68.3 ± 14.3 and 55.1 ± 10.7 kg, p = 0.001) and height (175.7 ± 7.4 and 162.4 ± 8.8 cm, p = 0.001). Conclusion. Irkutsk adolescent boys experience voice mutation at the ages of 12–13 years due to a decrease in the thyroid cartilage angle, with a vocal fold length of over 2 cm, which can be measured via ultrasound. From the age of 13 years, a difference is observed in the vocal fold length between boys and girls, correlating with increased weight and body mass index in both sexes