During adolescence, the larynx gets bigger and the vocal cords are lengthened and thickened. This makes the voice deeper in boys. The increased larynx occurs as a protruding part in some boys and is known as Adam's apple. Sometimes, the muscles of the growing larynx go out of control and the voice grows hoarse; however, it becomes normal after some time. In girls, the larynx grows bigger as well, but the growth is not as much as in boys. Generally, girls have a high-pitched voice because of this change.