Estimation of equivalent noise exposure level using hearing threshold levels of a population

Sudden Hearing Loss in the Active Duty Population: An Epidemiological Study

INTRODUCTION

Hearing loss among military personnel is a well-known challenge, reported as the second most common VA service-connected disability. Although most hearing loss occurs gradually, a subset occurs suddenly and significantly impacts quality of life and military readiness and is considered as a medical emergency. This study aims to evaluate the incidence of sudden hearing loss among different subpopulations within the military system to better identify at-risk groups.

MATERIALS AND METHODS

This study was a retrospective population-based study reviewing all cases of diagnosed sudden hearing loss between January 1, 2016 and December 31, 2021 within active duty service members in the U.S. DoD. Statistical analysis of multiple subpopulations was performed.

RESULTS

There were 2,650 cases of sudden hearing loss diagnosed in active duty service members during the study period, with an average incidence of 32.9 cases per 100,000 people per year, compared with 5 to 27 cases per 100,000 people per year reported in civilian populations. Senior officers demonstrated significantly increased rates of sudden hearing loss with 103.9 cases per 100,000 people per year, likely as a result of increased age, as did Air Force personnel with 45.1 cases per 100,000 people per year. There was no difference in incidence based on military occupational specialty, though service members located overseas were noted to have decreased incidence compared with those stationed within the USA. There was no significant difference during the years before coronavirus-19 pandemic (2016-2019) compared to the years following the start of the pandemic (2020-2021).

CONCLUSIONS

Sudden hearing loss appears to occur more frequently in military personnel than in the civilian population. The increased incidence in senior officers is likely driven by increased age, though further evaluation into the discrepancies between reported incidence of hearing loss among enlisted service members and officers is warranted. Although military occupational specialty did not demonstrate any significant difference in incidence, for thus far unknown reasons those in the Air Force demonstrated increased rates of sudden hearing loss. Although other potentially at-risk groups were identified, focused efforts to better understand contributing factors to elevated incidence in senior officers and Air Force personnel will help to better mitigate the incidence and effects of sudden hearing loss.

Noise of military weapons, ground vehicles, planes and ships

Noisy equipment and processes are found throughout military operations, exposing service members to risks of hearing damage due to hazardous noise levels. This article provides an overview of the military noise environment for the non-expert and provides a general characterization of the noise by source type and operational category. The focus of the article is primarily related to the Army, but the same, or similar, equipment is used by the Navy, Marine Corps, and Air Force. Damage risk criteria used by the Army Public Health Command are discussed. In addition, the important role of hearing protection to mitigate the hazards of noise exposure is provided.

A retrospective analysis of noise-induced hearing loss in the Dutch construction industry

Purpose

Noise exposure is an important and highly prevalent occupational hazard in the construction industry. This study examines hearing threshold levels of a large population of Dutch construction workers and compares their hearing thresholds to those predicted by ISO-1999.

Methods

In this retrospective study, medical records of periodic occupational health examinations of 29,644 construction workers are analysed. Pure-tone audiometric thresholds of noise-exposed workers are compared to a non-exposed control group and to ISO-1999 predictions. Regression analyses are conducted to explore the relationship between hearing loss and noise intensity, noise exposure time and the use of hearing protection.

Results

Noise-exposed workers had greater hearing losses compared to their non-noise-exposed colleagues and to the reference population reported in ISO-1999. Noise exposure explained only a small proportion of hearing loss. When the daily noise exposure level rose from 80 dB(A) towards 96 dB(A), only a minor increase in hearing loss is shown. The relation of exposure time and hearing loss found was similar to ISO-1999 predictions when looking at durations of 10 years or more. For the first decade, the population medians show poorer hearing than predicted by ISO-1999.

Discussion

Duration of noise exposure was a better predictor than noise exposure levels, probably because of the limitations in noise exposure estimations. In this population, noise-induced hearing loss was already present at the beginning of employment and increased at the same rate as is predicted for longer exposure durations.