A phonation disorder is a problem with pitch, loudness, or intensity that originates in the vocal folds of the larynx. Phonation disorders may be "functional", caused by continuous yelling or throat clearing, excessive smoking, or speaking at an abnormally low frequency or pitch. The results may be an increased size or thickening of the vocal folds, lesions or polyps on the vocal folds, or problems with elasticity of the larynx. In these cases, the treatment involves resting the voice and learning to speak at optimal pitches and volumes, as well as eliminating external causes such as smoking. Phonation disorders may also be "organic", due to viral growths, cancer, paralysis of laryngeal nerves, surgical intubation, or external traumas such as being hit in the throat with a baseball. These problems may require surgical removal of growths or reconstruction of the larynx, accompanied by voice therapy (Boone 287-96).