Until recently, most hearing conservation programs, including those in the military, have used permanent shifts in the pure-tone audiometric threshold as the gold standard for measuring hearing impairment in noise-exposed populations. However, recent results from animal studies suggest that high-level noise exposures can cause the permanent destruction of synapses between the inner hair cells and auditory nerve fibers, even in cases where pure-tone audiometric thresholds eventually return to their normal pre-exposure baselines. This has created a dilemma for researchers, who are now increasingly interested in studying the long-term effects that temporary hearing shifts might have on hearing function, but are also concerned about the ethical considerations of exposing human listeners to high levels of noise for research purposes. One method that remains viable to study the effects of high noise exposures on human listeners, or to evaluate the efficacy of interventions designed to prevent noise-related inner ear damage, is to identify individuals in occupations with unavoidable noise exposures and measure hearing before and as soon as possible after exposure. This paper discusses some of the important factors to be considered in studies that attempt to measure acute hearing changes in noise-exposed military populations.

Objective Information is summarized from the overall body of published literature regarding ototoxic chemicals encountered outside of clinical exposures, largely in occupational settings. While summarizing the most common non-pharmaceutical ototoxins, this review provides clinically relevant information and recommendations such that hearing health professionals may adopt a more comprehensive and appropriate diagnostic case history, test battery, documentation scheme, and education delivery. Methods Solvents, metals, and asphyxiants literature was reviewed using PubMed, national and international agency websites, and communications with known ototoxicity experts. Results Initial intentions to summarize the existing programs for occupational ototoxicity monitoring fell short when it was discovered that such programs have not yet formalized across the major oversight agencies in the United States. Instead, recommended guidance documents and fact sheets, which highlight existing occupational exposure limits and suggest monitoring and education are discussed. Conclusions While evidence in humans is limited, potentially ototoxic substances are worthy of improved surveillance and further research to understand their ototoxic mechanisms, effects, and possible mitigation strategies. A triad approach of monitoring, protecting, and educating is recommended for effective prevention of hearing loss: the Department of Defense Hearing Center of Excellence’s Comprehensive Hearing Health Program model employs such an approach.

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Purpose The purpose of this review article is to discuss how boothless audiometry may help address changes in hearing health care services and provide progressive tools to expand beyond traditional audiology clinic visits. The primary drivers for these changes include the COVID-19 pandemic, our aging population, comorbid effects of unidentified hearing loss, and the critical need for effective communication between patients and providers. This review article highlights key features and technical specifications of boothless audiometry, provides an overview of Food and Drug Administration (FDA)–approved boothless audiometry products, and describes how to leverage these products to increase access to hearing health services across the continuum of health care. Method Boothless audiometry literature was reviewed using PubMed and audiometry technology websites. FDA-approved boothless audiometry products were reviewed, and audiological features were categorized. Civilian and Department of Defense subject matter experts were consulted. Conclusions Boothless audiometry technology introduces opportunities for early audiometric assessment outside of the audiology clinic, in settings where traditional testing has been less possible, or even impossible, such as military environments, clinic waiting areas, schools, and nursing homes. This technology allows health care providers to identify individuals with significant hearing loss early and seek comprehensive services to prevent and treat hearing loss. By expanding the current hearing health care delivery model via boothless audiometry technology, the following benefits may be achieved, which can result in better outcomes overall: increased access to care, early identification and treatment of hearing loss, and reduced impact from the comorbid effects of hearing impairment.

Noise exposure is encountered nearly everyday in both recreational and occupational settings, and can lead to a number of health concerns including hearing-loss, tinnitus, social-isolation and possibly dementia. Although guidelines exist to protect workers from noise, it remains a challenge to accurately quantify the noise exposure experienced by an individual due to the complexity and non-stationarity of noise sources. This is especially true for impulsive noise sources, such as weapons fire and industrial impact noise which are difficult to quantify due to technical challenges relating to sensor design and size, weight and power requirements. Because of this, personal noise dosimeters are often limited to a maximum 140 dB SPL and are not sufficient to measure impulse noise. This work details the design of a body-worn noise dosimeter (mNOISE) that processes both impulse and continuous noise ranging in level from 40 dBA-185 dBP (i.e. a quiet whisper to a shoulder fired rocket). Also detailed is the capability of the device to log the kurtosis of the sound pressure waveform in real-time, which is thought to be useful in characterizing complex noise exposures. Finally, we demonstrate the use of mNOISE in a military-flight noise environment.Clinical Relevance-On-body noise exposure monitoring can be used by audiologists, industrial hygiene personnel, and others to determine threshold of injury, adequate hearing protection requirements and ultimately reduce permanent noise-induced hearing loss.