The voice box or the larynx begins to grow during puberty. The growth is more in the boys and the larynx can be seen as the protruding part of th throat. The protruding part is known as the Adam's apple. The voice of the boys becomes deep. In boys the voice becomes hoarse temporarily because of the out of control growth of muscles of the voice box. The voice box is growth is less in girls and they have a high pitched voice.