Question

why do and how voice changes in adolescence?

Answer 1

because when we undergo adolescence,our voice box enlarges and due to this our voice gets deeper and heavier

Answer 2

It's the larynx (or voice box) that's causing all that noise. The larynx, which is located in the throat, plays the major role in creating the sound of the voice. Two muscles, or vocal cords, are stretched across the larynx and they're kind of like rubber bands. As the body goes through puberty, the larynx grows larger and thicker. It happens in both boys and girls, but the change is more evident in boys. Girls' voices only deepen by a couple of tones and the change is barely noticeable. Boys' voices, however, start to get significantly deeper.

Hope this helps :)