Under the influence of androgens, the change in voice pitch that occurs in adolescent males is because of a growth spurt in the larynx. The growth of the larynx is more evident in boys, leading to a drop in the male voice of about one octave. The larger vocal folds of males are probably responsible for them having a lower fundamental frequency. Typically, the voice change in boys takes place before the appearance of noticeable facial hair by months and even sometimes years.
See Adolescent growth spurt, Androgen, Axillary hair, Fundamental frequency (F₀), Larynx, Mutation (speech), Puberty, Vocal folds