Hearing Conservation in Military Operations

An article on my profession.

This is an article I recently wrote with one of my colleagues on the primary role of audiologists in the military. Hazardous noise is a stressor that can cause permanent damage to the auditory mechanism, brain, and other parts of the body regardless of how tough and resilient a person may be. Like psychological stress, the impacts of noise are often painless but progressively take their toll over time. Awareness and effective intervention are essential to combat the permanent damage that can result from unprotected exposure. Understanding a stressor and the controllable measures to prevent harm is the goal of anyone looking to maximize performance in life.

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Hearing Conservation in Military Operations

US Navy sailors and civilian personnel operating on a flight line during takeoff.

“The views expressed in this Article are those of the authors and do not necessarily reflect the official policy or position of the Defense Health Agency, Department of War, nor the U.S. Government.”

Active-Duty Navy Audiologists are Naval Officers who apply their specialized skill sets and serve as subject matter experts in hearing conservation and communication sciences to address auditory, vestibular, and human performance challenges across the fleet. Their mission is to increase medical readiness and optimize performance in all combat and training environments through advancements in safety program management, preventive health education/training, overseeing audiometric monitoring, hearing and head protection devices, communication systems, and auditory performance factors.

Historical Context

Audiology as a profession, and hearing conservation as a discipline, both emerged largely in response to war-time hazardous noise exposures. All our nation’s wars dating back to early colonization show evidence of hearing loss as a battlefield injury. Efforts, however, to study the effects of noise exposure and provide aural rehabilitation to warfighters did not begin in earnest until WWII. It wasn’t until the 1970s and early 1980s that we began to see the emergence of formal Hearing Conservation Programs.

Operational Importance

US Marines firing a M777 155 mm Towed Howitzer

Unrestricted hearing is imperative to mission success in all military operations. Medical Readiness is defined as a service member’s ability to deploy and perform their assigned duties without preventable medical or dental limitations. Situational awareness and communication capability are the most important mechanisms for military members to operate safely and competently individually and as a team in dynamic environments. Both mechanisms rely heavily on the ability to hear well. In ideal lighting, our hearing allows us to detect cues or threats from any angle and outside of our immediate visual field. Normal hearing becomes even more crucial for situational awareness with less-than-ideal lighting due to time of day or environmental factors. Mild hearing loss can compromise the ability to understand speech, especially when visual cues are not available such as when focusing on a task or speaking through a communication device. Hearing in the presence of background noise creates additional challenges for both individual and mission effectiveness because it places an increased processing burden on the peripheral and central auditory systems to decipher what is important and what is just noise.

Health Impacts of Noise-Induced Hearing Loss

Noise-induced hearing loss (NIHL) is permanent damage to the auditory system caused by hazardous noise. At an approximately 10-15% prevalence rate, noise-induced damage is the most prevalent injury in the military every year (Navy and Marine Corps Public Health Center, 2016). NIHL is often characterized by poor speech understanding, difficulty hearing in background noise, difficulty locating sounds and tinnitus. Tinnitus is the perception of sound in the absence of an external auditory source. For decades, tinnitus and NIHL have been among the most prevalent disabilities within the Department of Veterans Affairs (Department of Veterans Affairs, 2024). This is because noise is one of the most prevalent hazards throughout military operations whose effects are often painless and progressive. While advancements in technology and capabilities have allowed our military to be more adaptive and multifunctional, they have also caused our hazardous noise environment to become more dynamic.

In addition, there are many non-auditory effects to noise-induced damage, which are often overlooked. NIHL is directly linked to psychological effects, cardiovascular effects, cognitive and sleep disturbances, social and occupational impacts, increased stress, and disruptions in overall quality of life (Basner et al., 2014; Lin et al., 2013; Jo & Baek, 2024; Wang, 2020).

Hazard Assessment and Measurement

US Marine firing a Squad Automatic Weapon (SAW)

Hazardous noise is generally determined by the overall intensity/loudness of the noise, duration of exposure, and noise type (continuous/steady-state, peak/impulse or a combination of the two). It can also include spectral quality/frequency content of the noise for unique or especially hazardous environments. Service members are required to be in the Hearing Conservation Program if exposed to continuous noise equal to or greater than 85 dBA as an 8-hour time-weighted average (TWA) and/or impulse noise equal to or greater than 140 dBP. The military uses a 3 dBA exchange rate, meaning a 3 dBA increase in continuous hazardous noise exposure cuts the exposure limit in half before the same risk of damage occurs. The table below demonstrates this exchange rate. As the table demonstrates, once an individual approaches exposures of 112 dBA or greater, it takes less than one minute for this exposure to risk causing NIHL.

(NIOSH, 1998)

Sound level meters can be used to measure all aspects of hazardous noise instantaneously and/or over time for a particular environment or piece of equipment. Noise dosimeters can also be worn by personnel to calculate the TWA as they engage in the dynamic environments they are assigned. This data allows general estimations of noise hazard risk level, however, small changes in an operation (i.e. addition or subtraction of a process or part, location of equipment or personnel, number of systems running, weather/climate and individual variability, etc.) can alter the noise environment and subsequently change the risk profile for a particular location or occupational specialty.

In the military, there are varying levels and types of hazardous noise. Dynamic occupational noise environments (rockets, grenades, explosives, missiles, aircraft, tanks, amphibious and land attack vehicles, etc.) and current limitations of hearing protective device (HPD) performance all increase the risk of NIHL. Examples of the decibel range for common military devices, tools, and aircraft are as follows:

• M4 Rifle: 158-165 dBP

• .50 Caliber: 153-155 dBP

• Mortars: 175-179 dBP

• Rockets: 180-185 dBP

• H-53 Helicopter: 109 dBA

• AH-1 Helicopter: 108 dBA

• V-22 Tiltrotor Aircraft: 120 dBA

• F-18 Fighter Jet: 130-150 dBA

• F-35 Fighter Jet: 153 dBA

• Needle Gun: 90-115 dBA

Each of these sound levels can produce permanent hearing damage within seconds to minutes of exposure when adequate hearing protection is not used.

Individual risk of NIHL will vary significantly due to many factors aside from the environment and HPD usage. Factors influencing susceptibility can also include genetics, prior exposure/damage, pre-existing hearing loss or tinnitus, sensitivity to sound, ototoxic medications, and exposure to other ototoxic agents (e.g. jet fuel, various solvents and chemicals commonly used in military operations).

Protection Challenges: Training and Proper Usage

Enrollment in a hearing conservation program involves audiologic monitoring, hearing conservation education, and hearing protection requirements. Audiologic monitoring allows for early identification of damage while education intends to prevent the problem before it happens.

Training for hearing protection devices varies on the worksite and familiarity of the safety managers or workplace supervisors. It is common for military personnel to not wear hearing protection within the recommended levels of attenuation, wear them inappropriately, or be exposed for longer durations than recommended. These factors increase the risk of noise-induced hearing loss. Therefore, proper training and fit verification should be conducted to reduce variability in hearing protection effectiveness and decrease the risk of NIHL.

While under-protection or inadequate usage of hearing protection devices is certainly a cause for the prevalence of hearing damage throughout the military, there is also the issue of over-protection. Just as hearing loss causes detrimental effects to safety, survivability and lethality, wearing too much hearing protection immediately causes the same problem. This issue is most common with more manageable noise hazards like rotary aircraft. If hearing protection configurations reduce hazardous noise for an exposed service member too far below 85 dBA, then situational awareness and communication capability can also be significantly impacted. This over vs under-protection dilemma contributes to the importance of command safety leaders and workplace supervisors to select the appropriate and specific criteria to determine administrative controls and hearing protection configurations.

Fit, comfort, and performance needed for the job are essential considerations when selecting hearing protection. The goal is always to protect a given worker while maintaining or enhancing their performance.

Conclusion

Effective hearing conservation in military operations requires a comprehensive, evidence-based approach that balances force protection with operational effectiveness. Navy Audiologists serve as critical enablers of mission success by providing expert guidance on hazard assessment, implementing tailored hearing protection strategies, and ensuring service members maintain the auditory capabilities essential for situational awareness and communication in combat environments. As military technology continues to advance and noise environments become increasingly complex, the role of audiological expertise in preserving both the health and combat readiness of our warfighters has never been more vital.

Success in this mission demands ongoing collaboration between audiologists, command leadership, safety managers, and individual service members to ensure hearing conservation programs are not merely regulatory requirements but are integrated components of operational culture. By protecting our personnel’s hearing today, we safeguard their ability to serve effectively throughout their careers and preserve their quality of life long after their military service concludes.​​​​​​​​​​​​​​​​

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References:

Basner, M., Babisch, W., Davis, A., Brink, M., Clark, C., Janssen, S., & Stansfeld, S. (2014). Auditory and non-auditory effects of noise on health. Lancet (London, England), 383(9925), 1325–1332. https://doi.org/10.1016/S0140-6736(13)61613-X

Department of Veterans Affairs. (2024). Fiscal year 2024 annual benefits report. https://www.benefits.va.gov/REPORTS/abr/docs/2024-abr.pdf

Navy and Marine Corps Public Health Center. (2016). Hearing Conservation Compendium Report CY2015. https://www.med.navy.mil/Portals/62/Documents/NMFA/NMCPHC/root/Documents/oem/Hearing-Conservation-Compendium-Report-CY15.pdf?ver=_OH0q-JxiFVUNHIouQnYsw%3d%3d

National Institute for Occupational Safety and Health. (1998). Criteria for a recommended standard: Occupational noise exposure: Revised criteria 1998 (DHHS (NIOSH) Publication No. 98-126). U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention. https://www.cdc.gov/niosh/docs/98-126/default.html

Lin, F. R., Yaffe, K., Xia, J., Xue, Q. L., Harris, T. B., Purchase-Helzner, E., Satterfield, S., Ayonayon, H. N., Ferrucci, L., Simonsick, E. M., & Health ABC Study Group (2013). Hearing loss and cognitive decline in older adults. JAMA internal medicine, 173(4), 293–299. https://doi.org/10.1001/jamainternmed.2013.1868

Jo, H., & Baek, E. M. (2024). Impacts of noise-induced hearing loss on sleep, health, and workplace: Multi-group analysis. Heliyon, 10(9), e30861. https://doi.org/10.1016/j.heliyon.2024.e30861

Wang, T. C., Chang, T. Y., Tyler, R., Lin, Y. J., Liang, W. M., Shau, Y. W., Lin, W. Y., Chen, Y. W., Lin, C. D., & Tsai, M. H. (2020). Noise Induced Hearing Loss and Tinnitus-New Research Developments and Remaining Gaps in Disease Assessment, Treatment, and Prevention. Brain sciences, 10(10), 732. https://doi.org/10.3390/brainsci10100732