The vocal cords (vocal folds) are composed of pliable shelves of tissue that are stretched horizontally across the voice box (larynx). The larynx is located in the neck, at the top of the windpipe (trachea). As air is pushed through the partially closed vocal folds, the outer covering of the vocal folds, known as the mucosa, vibrate. The cyclic vibration of the vocal fold mucosa creates a mucosal wave that is essential to the production of a normal voice. Any abnormality that disrupts the mucosal vibration causes a hoarse voice (dysphonia).