“We are working at creating hearing protection that is easier to use, is more comfortable to wear for really long periods of time and doesn’t deprive the soldier, sailor or airman of their need to communicate,” Yankaskas said. Most military members in high-noise areas now have access to custom-molded silicone earplugs. “The VA has really taken a proactive stand with technology such as active noise reduction [ANR] and custom ear molds,” Fox said. Silicone earplugs, created specifically for one military member, are designed to fit perfectly inside the external auditory. But even custom plugs can block essential outside noise and inhibit communication, so some military members, including pilots, now wear custom ear molds with radio communications embedded directly into the ear piece.
Explore This IssueJanuary 2013
Meanwhile, the Navy’s Noise-Induced Hearing Loss program continues to investigate improved forms of hearing protection. “In one of our earlier projects, we were using a next generation low-power cochlear implant. In that came a signal processor, and the signal processor is smart enough so that it can differentiate gunfire from voice. It could shut down those bands for the proper length of time, so you don’t hear the gunfire, then enable normal conversation,” Yankaskas said. “We called it intelligent filtering. It’s tricky, though, because the brain does a lot of signal processing on its own, and putting that in a chip is a challenge.”
The Noise-Induced Hearing Loss Program and the DOD’s Hearing Center of Excellence are also investigating genetic susceptibility to hearing loss. “To date, we know that there are about 60 genes involved in hearing loss,” said Yankaskas. “We’re not sure how they all play together.” It is hoped that current animal studies will further advance the understanding of genetic susceptibility, allowing researchers and clinicians to better protect the hearing of vulnerable service members.“We are currently running some protocols to try to determine if there are people who ought to have different types of hearing protection or be taken out of certain sound environments before damage occurs,” Dr. Packer said. Even the possibility of genetic testing for susceptibility to hearing loss brings up a host of ethical issues. “It’s a bit of a sticky situation,” Dr. Packer said, “because you don’t want to necessarily discriminate on job opportunities. Some high-noise jobs have more pay or promotability attached to them.”
While the military continues to refine hearing protection, it also carefully tracks the hearing of those who serve. Currently, each branch of the service assesses an individual’s hearing as part of an overall military readiness program. “Just as individuals have to see a dentist and have their teeth assessed so we know that they’re not going to fall apart when the individual is deployed somewhere, troops have to have an audiogram that doesn’t show a significant loss or change so they can go to war and do their duties there,” Dr. Packer explained. “All of the services perform a periodic hearing assessment screen, depending on what line of work the individuals are in, and that’s a database called the Defense Occupational and Environmental Health Readiness System–Hearing Conservation. Anybody who is identified as working in a noise environment will have an initial audiogram … and then an annual audiogram to look for temporary or permanent shifts. They’re then triggered for further care and follow-up based on how they do in the program.”