Background: Standard hearing protective devices were developed to prevent hearing loss resulting from occupational and recreational noise exposures. The existing auditory risk models that are used to predict hearing loss are very inaccurate when applied to the extreme conditions encountered in the modern military service environment.

Objective: The objective of this study is to improve and extend our understanding of auditory injury from blast and noise, thereby promoting the development of new technologies to prevent and mitigate injury to the auditory system and enhance techniques for assessing auditory protection systems.

Specific Aims: (1) Develop a neuro-functional understanding of acoustic injury encompassing the dynamics of the peripheral auditory system, through sensory transduction, to central auditory processing. (2) Develop an animal model, correlating human and animal auditory mechanisms and physiological responses to noise and blast events. (3) Develop a robust, validated system for the evaluation of hearing protective systems across the broad range of intensities and frequency spectra seen in real-world exposures.

Study Design: (A) Measure pressures in the external auditory canal and intracranial space of a post-mortem human surrogates and chinchilla head exposed to blast overpressure generated by a shock tube. (B) Predict neuronal damage correlated peripheral and central auditory function by measuring auditory responses of the chinchilla model, specifically hair cell function.

Relevance: This study improves and validates auditory hazard models and testing algorithms permitting better assessment of protective systems and therapeutic strategies for both blast exposure and high intensity noise.