Thyroarytenoid(TA), lateral cricoarytenoid(LCA), and IA muscles are referred to as the adductors of the vocal fold. While TA is known to shorten the vocal folds and adducts the membranous vocal fold, LCA adducts the inter-vocal process region and IA adductes the posterior commissure. Even though IA has an important role for the positioning the vocal folds during respiration and phonation together with the action of the posterior cricoarytenoid muscle, little is known about the effect of IA on voice parameters during phonation. An in vivo canine model was used in five mongrel dogs to exmine the role of the IA muscle in controlling phonation. Two out of five dogs, sound could not be elicited without stimulating IA branches of the recurrent laryngeal nerves. When IA was stimulated dynamically and statically, subglottic pressure, vocal intensity and fundamental frequency were increased.