Hidden Hearing Injury: The Emerging Science and Military Relevance of Cochlear Synaptopathy

Abstract

Neurological injuries resulting from noise exposures via the auditory system have potentially significant implications for military Service Member performance, long-term Veteran health, and noise exposure standards. Mediated via auditory pathways, such injuries have possible relationship to clinical impairments including speech perception, and may be a largely overlooked contributor to cognitive symptoms associated with other military service-related injuries such as blast exposure and brain trauma. The potential health and performance consequences of noise-induced cochlear synaptopathic injury are easily overlooked, especially if it is assumed that hearing threshold sensitivity loss is the major concern. There should be a renewed impetus to further characterize and model synaptopathic mechanisms of auditory injury; study its potential impact on human auditory function, cognition, and performance metrics of military relevance; and develop solutions for auditory protection (including noise dosimetry) and treatment if appropriate following noise or blast exposure in military scenarios. We identify specific problems, solution objectives, and research objectives. Recommended research calls for a multidisciplinary approach to address cochlear nerve synaptopathy, central (brain) dysfunction, noise exposure measurement and metrics, and clinical assessment.