Most of the voice change begins around puberty. Adult pitch is reached 2–3 years later, but the voice does not stabilize until the ages of 21–25. It usually happens months or years before the development of significant
facial hair. Under the influence of
sex hormones (namely
testosterone), the voice box, or
larynx, grows in both sexes. This growth is far more prominent in males than in females 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. The facial bones begin to grow as well. Cavities in the
sinuses, the nose, and the back of the
throat grow bigger, thus creating more space within the head to allow the voice to resonate. Occasionally, voice change is accompanied by unsteadiness of vocalization in the early stages of untrained voices. Due to the significant drop in pitch to the
vocal range, people may unintentionally speak in
head voice or even
strain their voices using pitches which were previously
chest voice, the lowest part of the
modal voice register. == History of voice cracks ==