Thyroplasty is a phonosurgical technique designed to improve the voice by altering the thyroid cartilage of the larynx (the voice box), which houses the vocal cords in order to change the position or the length of the vocal cords. Types There are four different types of thyroplasty procedures described by Isshiki: Type 1 thyroplasty – Medialization of the vocal folds (most common surgery for unilateral vocal cord paralysis). [Source: Wikipedia ]