What causes deepening of the voice in puberty?

During puberty, the voice deepens primarily due to the growth and maturation of the larynx, or voice box, which is influenced by increasing levels of testosterone in males. This hormone causes the vocal cords to lengthen and thicken, resulting in a lower pitch. Additionally, the shape of the vocal tract changes, further contributing to the deepening of the voice. Similar changes occur in females, though to a lesser extent, as their voices may also become slightly deeper.