The roar of fighter jets taking off from an aircraft carrier is one of the most iconic sounds of the United States Navy. But for the brave men and women who work in these high-decibel environments day in and day out, the noise can take a devastating toll on their hearing.
There is no other injury more reported than hearing damage,” according to Lt. Cmdr. Kyle Shepard, a resident audiologist at the Naval Air Warfare Center Aircraft Division (NAWCAD). Tinnitus and hearing loss is our military’s first and second most-reported disability.”
Aircraft and equipment are loud. Consider the blare of an aircraft carrier’s engine room or flight deck, where the deafening noise of equipment and aircraft blend together. For our military, it is an endless soundtrack that plays along to their four or more years of service. Despite the severity of the problem, however, finding a solution has proven challenging.
Hearing damage happens gradually over time, meaning that service members can cope with hearing loss that happens slowly across the span of their career until one day they cannot.
“Noise-induced hearing loss is a readiness issue affecting at least 10 percent of our military,” Shepard said. “We’ve seen aviators and aircrew who just don’t notice the small amount of hearing loss until one day it adds up, and they struggle to hear and communicate from the cockpit or maintain situational awareness on the flight line or battlefield.”
The current standard for hearing protection in the Navy is one-size-fits-all foam earplugs and earmuffs, which can be ill-fitting, uncomfortable and sometimes ineffective. Education surrounding hearing protection also varies, and the use of these devices can interfere with aircrew members’ ability to hear and communicate with each other. Overall, there is significant variability in how hearing protection is used on today’s flight line. A choice solution is custom hearing protection, but the Navy’s current process delivering custom hearing protection is difficult and cumbersome.
“Custom hearing protection has been around for some time,” Shepard said. “But the current process by which we take physical impressions today—injecting and extracting silicone putty into a sailor’s ear, sending impressions off to a manufacturer for weeks or months of production, and getting them back to a sailor somewhere out in the fleet—is a system ripe for modernization, and that’s what we’ve tackled at NAWCAD.”
The modernized process involves digital scanners and 3D printers. What’s more, the Navy has validated that it could eventually have the option to fit any sailor for custom hearing protection the day they fit for their first uniform.
“Audiologists across the Navy agree the best hearing protection is one a sailor is most comfortable using, fits and is appropriate for the environment they operate in,” Shepard said. “We’ve seen that custom earplugs can provide improved consistency and sometimes better attenuation than standard earplugs because they conform to ear anatomy—they’re much easier to insert with less fit variability too.”
“Several large medical commands are already 3D-printing biomedical material like prosthetics,” Shepard said. “The only missing pieces are a digital ear scanner and imaging software which will enable our independent manufacturing of custom hearing protection in the military.”
The scanner is commercial and features a small probe that inserts into a sailor’s ear to capture a digital image of the ear canal. This offers sailors a faster, safer and more comfortable fitting experience compared to the current method of custom fittings. The current process involves injecting silicone into the ear canal, waiting for it to set and then carefully extracting the molds. This is slow, tedious, and sometimes painful or dangerous process, especially if a sailor has a small or uncommonly shaped ear canal, sensitive ears or other anatomical challenges.
“I’ve taken more than 1,000 physical impressions and I’ve still had close calls with aircrew who have had extremely uncomfortable fittings—one that required a shot of lidocaine to finish the extraction because I just couldn’t see unique anatomical contraindications deep in the ear canal with our legacy equipment,” Shepard said.
In addition, silicone impressions require a certified audiologist, and only major commands and medical centers employ these professionals. Since the scanner is much safer and less invasive, the training is simpler and requires less experience.
“Most importantly, digital scans are safer, but they also cut custom hearing protection’s production by at least 50 percent,” he said. “With legacy silicone impressions, we’re not making the ear plug—we’re making the mold we mail away for a manufacturer to use in production. It can take two to six months to receive back the custom plugs at some of our international duty stations.”
The military’s move toward 3D printing offers yet another solution with custom hearing protection, which is what most manufacturers use for production anyways. Many Navy commands could print the plugs out immediately in-house, especially at commands where they have already integrated 3D printing in medicine. Today naval dentists print various prosthetics for sailors at sea and ashore.
Shepard and NAWCAD’s aeromedical engineers are ready to support any command interested in getting in touch to see how they can start offering custom hearing protection to their warfighters today.
“Let’s start getting after defense’s most reported injury. Where are our commands with the largest need? Our major training and medical commands already have the printers that we will eventually use for independent manufacturing of custom hearing protection. Reach out to me so we can get these scanners and training out there and expand the care our service members need.”
Article originally appeared on NAVAIR
