Adductor spastic dysphonia is a voice disorder characterized by a strained, squeezed, effortful voice produced by true and false cord hyperadduction. An in vivo canine model has been developed to simulate hyperadduction of the true cords. Using this model, the thyroarytenoid muscle was found to have a greater effect on intraglottic and subglottic pressure than cricothyroid muscle contraction. The intraglottic and subglottic pressure was reduced after simulated recurrent laryngeal paralysis. This model can be used in future studies to compare laryngeal treatment modalities for disorders that have a component of vocal cord hyperadduction, such as spastic dysphonia.