Changes in the male voice at puberty: vocal fold length and its relationship to the fundamental frequency of the voice.

Ultrasound measurements of the vocal folds were taken for a number of boys passing through puberty. The boys were grouped according to their pubertal stage as defined by Tanner and there was a gradual increase in the length of the vocal folds as puberty progressed. The fundamental frequency of the boys' speaking voice was recorded via laryngography and a good correlation between the length of the vocal folds and the frequency of the voice was seen. The sudden drop in frequency seen between Tanner stages 3 and 4 did not correlate with similar changes in the length of the vocal folds at this time but stroboscopic findings suggest a change in the structure and mass of the vocal folds at this time of maximum frequency change.