Puberum dysphonia is the normally voice changes adolescent males undergo due to a sudden increase in the length of the vocal cords due to the enlargement of the Adams apple (thyroid prominence) with puberty. This sudden increase in the length of the vocal cords is due to the sudden increase in testosterone levels found in pubescent males.
This is uncommon in females because their vocal cords do not show a sudden increase in length.
Under the influence of androgens, the voice box, or larynx, grows in both sexes. This growth is far more prominent in boys, causing the male voice to drop and deepen, sometimes abruptly but rarely "over night," about one octave, because the longer and thicker vocal folds have a lower fundamental frequency. Before puberty, the larynx of boys and girls is about equally small. Occasionally, voice change is accompanied by unsteadiness of vocalization in the early stages of untrained voices. Most of the voice change happens during stage 3-4 of male puberty around the time of peak growth. Full adult pitch is attained at an average age of 15 years.
Continuation of a high pitched voice beyond puberty is known as puberphonia.