Only You Can Prevent Hearing Loss

BY LT NICHOLAS MYERS, VAW-121

Lithographer Seaman Jared Benner, participates in an annual hearing test in an aviation medicine lab. As part of a vast health care system, the hearing conservation program is designed to monitor Sailors’style hearing abilities when their working environment is considered a high-level noise area. (Photo by Mass Communication Specialist 3rd Class Jason T. Poplin)

Lithographer Seaman Jared Benner, participates in an annual hearing test in an aviation medicine lab. As part of a vast health care system, the hearing conservation program is designed to monitor Sailors’style hearing abilities when their working environment is considered a high-level noise area. (Photo by Mass Communication Specialist 3rd Class Jason T. Poplin)

Naval Aviation is a noisy business, and as aviators it’s a hazard we have come to accept and mitigate through the use of hearing protection. With the introduction of new platforms and technologies there comes a time when we have to re-evaluate traditional hearing protection methods and adapt accordingly to prevent permanent disability.

Since the initial flights of the E-2D Advanced Hawkeye, aircrew recognized noticeably higher noise levels and increased crew fatigue throughout different regimes of flight. Many of these flights have led to hazard reports being generated and post-flight audiograms being performed to evaluate hearing change for that duration. The VAW-121 Bluetails conducted a noise study to collect additional data to help support the HAZREPs and give fleet feedback to assist the PMAs in allocating resources to address these issues. While collaborating with industrial hygiene specialists at Naval Medical Center Portsmouth, Va., the squadron was able to both collect this data and learn additional lessons about noise exposure that are applicable to all platforms fleetwide.

The scope of this study was to evaluate the magnitude of E-2D noise exposure to aircrew through multiple regimes of flight and determine if current hearing protection methods are sufficient across all frequencies in the aircraft. The Bluetails answered these questions throughout three flights, during which personal noise dosimeters were utilized and noise levels throughout the aircraft were evaluated with various handheld noise measuring devices provided by the industrial hygiene specialists. The flights were two to three hours long and conducted in various operating areas on the east coast. Some of the flight profiles evaluated were: max power in a climb, straight and level flight, left and right flat turns, and max power descent. Samples were taken during these profiles at various locations in the cockpit, forward equipment compartment (FEC), and the Combat Information Center.

The U.S. Department of Health and Human Services states that noise levels at or above 85 decibels can cause noise induced hearing loss (NIHL). To put this in perspective, a typical running vacuum cleaner produces 88 decibels. NIHL is the only type of hearing loss that is completely preventable with the proper use of personal protective equipment (PPE) and exposure time mitigation. The study concluded E-2D aircrews are being exposed to a time weighted average of 100 dBA, which requires an attenuation of 16 dBA to reduce personnel exposure below DoD criteria. While these average levels are acceptable with the proper wear of current hearing protection, there are circumstances where aircrew are subjected to peak noise levels exceeding the exposure threshold for permanent hearing loss while utilizing the recommended PPE. For instance, with a high power setting, straight and level at 200 KIAS, measurements taken at the pilot and co-pilot stations were 113 dBA and 108 dBA respectively. During this noise exposure it is common for aircrew to remove hearing protection to adjust fitment or switch from helmets to their alternate David Clark headsets. Additionally, within the same flight regime at 210 KIAS, noise levels at the FEC avionics rack reached 118 dBA. This area of the aircraft is often occupied during trouble shooting of avionics and radar pressurization systems or while utilizing the relief tube. To put these exposures in perspective, with no hearing protection it will take 56 seconds at 112 dBA to cause permanent hearing loss.

The study concluded that the noise exposure levels can be mitigated through the proper wear of double hearing protection; however, given the thin margin of protection afforded by current PPE, correct wear cannot be emphasized enough. The question regarding the cause of increased crew fatigue has yet to be answered and has led Naval Air Systems Command to investigate the possibility of the HGU-68 and HGU-84 helmets amplifying at-ear sound at low frequencies due to vibration.

The biggest takeaways for aircrew are to ensure you are following the manufacturers’ recommendations when installing earplugs to maximize effectiveness. Also, it is imperative to maintain the integrity of your hearing protection through proper fitment of flight equipment. Finally, aircrew must manage noise exposure by limiting the time PPE is removed and prioritize quieter regimes of flight if removal is necessary.

Noise induced hearing loss is completely preventable. Wear the correct hearing protection, wear it right, and wear it when needed. Only you can prevent your hearing loss.