At what age does a boys voice deepen?

Boys' voices typically start to deepen between the ages of 12 and 14, although this can vary. This process, known as voice breaking or mutation, is caused by changes in the vocal cords. During puberty, the vocal cords lengthen and thicken, which lowers the pitch of the voice. The voice may also become hoarse or crackly during this time, which is normal. Eventually, the voice will settle into a lower register.