Testosterone causes a pubescent boy's voice to deepen. This happens between 12 and 14 years of age. At this time, testosterone affects the larynx (voice box). The larynx grows larger and the vocal cords change. The larynx is the bulge on the front of a boy or man’s neck, known as the Adam’s apple. This change can occur quickly or take a few months. In the latter case, the boy's voice might crack at times, and this can happen at the worst moments. A boy might be embarrassed by his voice cracking, but don't worry. It is a normal part of puberty.
Not all boys and men wind up with the same deep voice; grown men’s voices can vary quite a bit, and not all are as deep as others, which is perfectly normal.
