Originating from the rehabilitation of noise-induced hearing losses (NIHL) incurred during World War I and II, the Department of Defense (DoD) has historically led the fields of hearing conservation and audiology   (Bergman, 2002).

In fact, the earliest hearing-conservation regulations came from the military services with the Air Force in 1956. The change that the U.S. Army made to the Army Hearing Program in 2008 to make hearing capabilities rather than hearing-loss prevention the primary focus has continued this tradition of innovation and leadership.

That leadership and innovation endure as significant changes continue to challenge the Military Health System. The United States (U.S.) military health-care systems have been reorganized under the Defense Health Agency (DHA). The DHA is a joint, integrated combat- support agency that delivers the quadruple aim of:

  1. Increased readiness, 
  2. Better health, 
  3. Better care, and 
  4. Lower cost.

The military has the latter three of these aims in common with our non-military audiology colleagues. Unique to the military is that our primary aim is readiness. We maintain physical, mental, and medical preparedness to deploy when needed, during both peacetime and wartime. 

While undergoing the largest merger of health-care systems ever attempted, the DHA has worked closely with the services to provide medical readiness and health-care delivery that is more integrated, efficient, and effective than ever before (U.S. Defense Health Agency, 2020). 

The Air Force, Army, and Navy have active duty (military), as well as civilian audiologists and technicians. We partner with industrial hygiene, public health, occupational health, and safety to deliver hearing-loss-prevention care. 

In 1978, military hearing-conservation programs were standardized across the three services with the publication of a U.S. Department of Defense Instruction (DoDI 6055.12, 2019). This document is updated periodically to provide guidance and requirements for hearing-conservation implementation. 

Although there are some differences among service programs, all the programs collaborate in many ways. The DoD Hearing Conservation Working Group has representatives from each service who provide expert consultation to the Department of Defense on noise control, hearing injury metrics/trends, hearing-loss prevention, and hearing-conservation research initiatives. 

At the direction of Congress, the DoD created the Hearing Center of Excellence (HCE) 10 years ago. The HCE is organized under the U.S. Defense Health Agency (2020) and provides hearing-health expertise to enhance operational performance, medical readiness, and quality of life.

TABLE 1. Comparison of Some Key Differences Between Occupational Safety and Health Administration and Department of Defense Regulatory Requirements

DIFFERENCES

OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION (OSHA)

DEPARTMENT OF DEFENSE (DoD) INSTRUCTION

When Hearing-Protection Device Required

90 dB

85 dB

Exchange Rate (Intensity/Duration)

5 dB

3 dB

Age Correction

Allowed

Prohibited

Use of Hearing-Protection Device for Quiet Period

Allowed

Prohibited

Hearing-Protection Fit Check

N/A

Recommended (soon to be required)

Certification

Technicians operating microprocessor audiometers do not require certification

Council for Accreditation in Occupational Hearing Conservation (CAOHC) certification or equivalent training is required to perform hearing test

Engineering and Administrative Controls

Initiated to reduce noise levels below 90 dB(A)

Initiated when feasible to reduce noise levels below 85 dB(A)

Consideration of Ototoxic Exposures

N/A

Required

 

At both the DoD and service levels, military hearing-conservation programs are more stringent than the Occupational Safety and Health Act (OSHA) in many of their requirements. TABLE 1 details some of those differences. For example, note that DoD requires hearing protection at 85 dB and uses a 3 dB exchange rate.

Hearing Conservation in the Military

Each of the military services has a public health organization that is responsible for its hearing-loss-prevention program. The U.S. Navy and Marine Corps public health services fall under the Navy Bureau of Medicine and Surgery. 

The Army Hearing Program is under the U.S. Army Public Health Center and the Air Force Hearing Conservation Program is under the public health branch of the Air Force Medical Readiness Agency. 

Due to significant noise exposures unique to warfighters, both the Army and Marine Corps have enrolled most of their own personnel in the Hearing Conservation Program (HCP) (U.S. Department of the Army, 2008; U.S. Department of the Navy, 2016). In the Navy and Marine Corps, comprehensive HCP implementation and management involves strong collaborative partnerships among military leaders, safety specialists, and medical (audiology) personnel. 

Shipboard HCPs are regularly assessed by the Navy’s Board of Inspection and Survey to evaluate preparedness for sea operations. Mishap investigations are  required after permanent threshold-shift occurrences. 

The Army Hearing Program has four main components: Hearing Readiness, Clinical Hearing Services, Operational Hearing Services, and Hearing Conservation. Each of these components complement each other to prevent NIHL and maximize safety and combat effectiveness.

Hearing Readiness 

In certain military occupational environments, distinct hearing and precise communications are critical; a lack of clear understanding can trigger serious consequences (U.S. Government Accounting Office, 2011). The inherent challenge is that service members' hearing must be protected from hazardous noise damage without compromising the ability to hear and communicate in complex and chaotic environments (U.S. Department of the Army, 2008).

Hearing readiness is designed  to ensure that military service members and noise-exposed civilians have the necessary hearing capability to perform their job-specific duties, as well as the appropriate and properly fitted hearing-protection devices (HPDs) for their mission. 

Annual audiometric tests are administered to HCP enrollees through a standardized DoD-approved microprocessor hardware and software system. Noise abatement/reduction efforts, annual hearing-conservation education sessions, and HPD fittings are important precursors for hearing readiness. While audiograms do not prevent hearing loss, audiometric test results serve as an effective lagging indicator of hearing readiness and hearing-loss-prevention success. 

DoD regulations require collaborative efforts between military operational leadership and medical leadership, leveraging the expertise of the audiologists and public health professionals to reduce noise hazards and prevent NIHL (U.S. Department of Defense Instruction, 2019). 

FIGURE 1. Percentage of service members with hearing impairment greater than 25 dB.
FIGURE 1. Percentage of service members with hearing impairment greater than 25 dB. Source: Hearing Health Surveillance Data Review (U.S. Department of Defense, 2019). 

The DoD provides hearing help to individuals, and sometimes groups of people, to enhance readiness and enable them to operate effectively as a team (i.e., during deployment). This is accomplished through hearing-loss-prevention outreach initiatives with noise-hazard commands, such as group education and hearing protection/communication device selection and fittings. These may focus on custom devices for various military specialties such as aviation, special operations, and military band members. 

In some military environments, obtaining and wearing the proper HPD can mean the difference between life and death. Therefore, it is imperative that the hearing health of DoD personnel is prioritized. Military personnel face unique challenges in training, flying, and combat situations and are exposed to hazardous noise from uncommon sources. This can include various military systems, machinery, vehicles, and weaponry. 

DoD Trends in Decreased Hearing Loss

After several years of increasing trends in hearing injuries at the turn of the 21st century (Institute of Medicine, 2006), one of the recent successes is an overall decrease in hearing loss for all DoD components. This improvement is associated with the implementation of multifaceted hearing-conservation programs administered by each service and the Hearing Center of Excellence (HCE) Comprehensive Hearing Health Program (CHHP). 

According to a tri-service hearing-health review (Institute of Medicine, 2006), the percentage of service members with hearing loss (defined as greater than 25 dB) decreased from 21 percent in 2012 to 15 percent in 2018 (see FIGURE 1). The percentage of DoD civilians enrolled in service hearing-conservation programs with hearing loss also decreased, from 51 percent in 2012 to 40 percent in 2018 (see FIGURE 2). 

Innovation

In support of the warfighter, the HCE, tri-service representatives, and associated DoD laboratories researched the impact of hearing loss on mission performance. The long-term goals of these efforts are to establish DoD accession (joining the military) and retention hearing-profile standards consistent with hearing-readiness requirements. 

FIGURE 2. Percentage of DoD civilians with hearing impairment greater than 25 dB.
FIGURE 2. Percentage of DoD civilians with hearing impairment greater than 25 dB. Source: Hearing Health Surveillance Data Review (U.S. Department of Defense, 2019). 

One ongoing effort that the Army is leading is the introduction of new fitness-for-duty criteria for hearing standards and use of the Military Operational Hearing Test (MOHT) to replace the Speech Recognition in Noise Test (SPRINT). 

The SPRINT was designed by the Army to predict communication difficulty in active-duty soldiers with hearing loss. The test includes either 100 or 200 pre-recorded monosyllabic words with multitalker babble (9 dB speech-to-babble ratio) delivered to both ears simultaneously. 

The MOHT is a test battery, developed by Dr. Doug Brungart at Walter Reed National Military Medical Center, for evaluating auditory fitness for duty. This testing is administered to service members with auditory thresholds that exceed a set of criteria and is a better indicator of performance in the presence of noise.

The MOHT is composed of three components: the diagnostic audiometric evaluation, an evaluation of speech-in-noise using the Modified Rhyme Test (MRT), and an evaluation of spatial awareness determined by administering the Spatial Digit Test (SDT).

The services are pilot-testing boothless audiometry in remote and/or deployed environments. The Army recently sent an active-duty audiologist overseas with boothless technology (in cooperation with the HCE). 

This proof-of-concept deployment yielded excellent results. The use of boothless audiometry is now being considered for implementation in multiple settings, such as point-of-injury care in remote locations and military operational environments.

The Navy is conducting a longitudinal study on hearing-protection checks to obtain personal attenuation ratings (PARs) and hearing-conservation training for Marines at recruit accession points. The Army is investigating fit-testing hearing protection prior to the use of excessively loud weapons. These are critical points in service members’ careers for providing vital, just-in-time, hearing-loss-prevention education. 

The Air Force is exploring the development of a deep-fitting in-the-ear noise dosimeter to monitor noise exposure and validate hearing-protection effectiveness more accurately.

As we have come to understand, a service member's dual need to protect hearing while maintaining situational awareness (this includes use of auditory information, with other sensory information, to understand/have an awareness of their environment) for operational performance, makes wearing hearing protection an ongoing challenge. 

To address this need, the HCE, through key partnerships, is developing an HPD Evaluated Products List (EPL) that will enable warfighters to select the best HPDs for specific operational tasks and individual needs. This initiative will develop and implement standardized methodology to evaluate hearing protection and tactical hearing-protective systems, enabling selection based upon hearing-critical tasks and hearing-protection characteristics. 

To date, the HCE and its partners have:

  1. Created and disseminated the evaluated passive HPD poster and guidebook to enable hearing-health professionals, industrial hygienists, and safety professionals to better select passive hearing protection appropriate for the noise environment and hearing-critical tasks service members perform, and 
  2. Developed and published a national standard that provides methods for assessing sound-localization performance for the open ear and with head-worn devices (ANSI/ASA S371-2019).

Partnerships between the DoD and industry are important to obtain improved hearing-protection technology that enhances communication while effectively suppressing hazardous noise for military-unique environments.

With improved HPD selection and continued hearing-health education, ideally, warfighters will overcome previous trends of non-use of up to 50 percent due to reported concerns with comfort and communication, will be more inclined to use HPDs, and the DoD will continue to witness a reduction of hearing loss across all services (U.S. Government Accounting Office, 2011).

Other DoD Hearing-Health-Care Initiatives 

Ototoxicity

Ototoxic chemical exposure evaluation and control are included in DoD regulatory requirements. Therefore, ototoxin risk assessments are incorporated as a component of DoD hearing-conservation programs. 

If ototoxic chemicals (i.e., jet fuel, toluene, etc.) or heavy metals (i.e., lead, chromium, etc.) are present in hazardous-noise areas, the increased risks of hearing loss are evaluated, considering the synergistic and individual effects of chemical and noise exposures.

Surveillance

When Congress mandated the creation of the HCE, it called for a registry to document and track service member hearing loss and auditory-system injury and share this information with the VA. Ultimately, the registry is a critical tool that allows the DoD and VA to assess the impact of best-practice initiatives on service member and Veteran hearing and balance health outcomes. 

The Joint Hearing Loss and Auditory System Injury Registry (JHLASIR) reached full operating capability on January 31, 2020. The registry’s benefits will continue to expand with the creation of new functionalities that provide an even broader resource for service member and Veteran hearing and balance health data. 

Conclusion

During a time of fast-paced organizational changes, the DoD continues to innovate and lead the way toward better hearing health for its military service members, civilians, and Veterans. These efforts have resulted in a decrease in the percentage of service members and civilians with hearing loss enrolled in hearing-conservation programs. 

To build on these successes, it is vital to foster continued collaboration among the services, as well as between military operational and medical leadership, in addition to partnerships between the DoD and industry. 

The DoD will continue to address unique challenges and prioritize hearing readiness to ensure military service members and civilians have the necessary hearing capability and appropriate hearing protection to enhance operational performance.  


Disclaimer

The views expressed are those of the authors and do not reflect the official policy or position of the Department of Defense or the U.S. Government.