Most of the voice change begins around puberty. Adult pitch is reached 2 -- 3 years later but the voice does not stabilize until the early years of adulthood. It usually happens months or years before the development of significant facial hair. Under the influence of androgens, the voice box, or larynx, grows in both sexes. This growth is far more prominent in boys than in girls and is more easily perceived. It causes the voice to drop and deepen. Along with the larynx, the vocal folds (vocal cords) grow significantly longer and thicker.
when does a boy's voice stop changing
the early years of adulthood