Project Summary/Abstract Primary muscle tension dysphonia is a voice disorder that involves excessive and poorly coordinated muscle activity affecting multiple subsystems that are involved in speech production, in the absence of structural or neurologic abnormalities of the larynx. Primary muscle tension dysphonia (MTD) is one of the most common forms of voice disorders, accounting for at least 40% of patients seen in voice clinics. Perceptually the voice sounds hoarse and strained, with reduced loudness and pitch range, and people with MTD find speaking very effortful and fatiguing. The physiological abnormalities that characterize MTD are considered multifactorial, and include over-activity of muscles in and around the larynx, laryngeal constriction patterns, and abnormal speech breathing patterns. However, standard treatment approaches for MTD primarily address laryngeal function, including repositioning of laryngeal structures, reducing activity in the intrinsic and extrinsic laryngeal muscles, and altering vibratory patterns. Although voice improvement may follow these treatments, many people with MTD show recurrence of voice problems after only a few months, and some do not improve with treatment. These findings highlight the need for alternative treatments that address the respiratory contributions to MTD, with training targets that are based on the specific physiologic deficits of the respiratory subsystem, which directly affect the phonatory system. The goal of this project is to determine the effects of respiratory-based treatment focused on altering lung volume levels in people with MTD, and compare those effects to a control condition. A randomized group design will be implemented to determine the respiratory and acoustic effects of each condition using training techniques with established efficacy in motor learning. We will determine the effects of each condition immediately after and then 3 and 6 months after treatment completion to assess short- and long-term treatment effects. We propose that altering the levels at which speech breaths are initiated and ended (lung volume initiation and termination) while speaking will have a positive effect on related laryngeal behavior and voice. The proposed project has the potential to substantially advance the evidence-based treatment options for MTD, providing a vital step toward reducing the debilitating effects of this disorder.