Project Summary The objective of this project is to investigate voice changes associated with speaking in challenging acoustic environments to better inform clinical care for individuals with voice disorders. Muscle tension dysphonia (MTD) is a common voice disorder that often results in difficulty communicating in daily life. Many people experience voice symptoms from speaking in noisy environments; for most, the symptoms resolve quickly. However, for those with MTD, voice symptoms often persist, making it difficult for them to meet their occupational and social vocal demands. The reasons for this persistence are unknown. Therefore, it is essential to elucidate the underlying mechanisms of voice production in noisy environments to optimize and individualize voice assessment and treatment for these individuals with MTD. Most speakers increase their vocal intensity while speaking in noisy environments, a phenomenon known as the Lombard effect. Speaking during and after exposure to a loud environment presumably requires monitoring of both background noise and one’s own voice, and then responding with vocal motor adjustments. This implies that sensorimotor integration is crucial in these real-life circumstances. There is preliminary evidence that individuals with MTD have atypical auditory-motor integration and an atypical persistence of Lombard responses after speaking in noise. However, no known studies have comprehensively characterized the underlying mechanisms and clinically relevant voice changes of the Lombard effect for those with and without MTD. To develop evidenced-based diagnostics and targeted voice treatments, we must better understand the processes and voice changes associated with speaking in daily life. Therefore, the specific aims of this project are to 1) investigate the sensorimotor mechanisms of the Lombard effect and 2) characterize clinically relevant voice changes associated with the Lombard effect for individuals with and without MTD within a communicative context. Sixty speakers (30 with MTD and 30 without) will complete a Lombard task to measure vocal responses and self-reported vocal effort while communicating during and after exposure to a noisy environment. Inexperienced listeners will rate overall severity of dysphonia for the speakers’ speech samples from the Lombard task. Lombard responses will be analyzed behaviorally and neuro- computationally, and they will be compared between the groups and across various stages of the Lombard task. Clinically relevant vocal measures (i.e., acoustic, self-reported vocal effort, and listener-auditory perceptual ratings of overall severity of dysphonia) of the Lombard task will be compared across groups and phases of the experimental task. This project is theoretically and clinically significant; it will fill in a substantial gap, providing theoretical insight into the sensorimotor mechanisms of MTD in real-life environmental contexts, and contributing to the clinical evidence to improve diagnostics and individualize treatment for those with sensorimotor deficits underlying their voice disorders.

Project Narrative The purpose of this project is to investigate voice changes associated with speaking in challenging acoustic environments to better inform clinical care for individuals with voice disorders. Many real-life communicative environments include background noise, which poses an obstacle for monitoring and regulating of voice production, especially for those with muscle tension dysphonia. This project, therefore, will fill a crucial theoretical knowledge gap of the underlying mechanisms of the Lombard effect and inform development of individualized clinical assessment and treatment for individuals with sensorimotor deficits underlying their voice disorders.