There are two ways to make custom ear protection, which can be personalized to include communication capabilities, Shepard said. The first uses a silicone model. The second is through 3-D scanning. If Shepard uses the silicone process, he’ll take an otoblock, a piece of soft material with a plastic wire attached to it, and place it in the ear canal around the second bend. The oto block protects the inner ear from the silicone, which will then be placed using a silicone gun that pushes a pink, rubbery goo into the ear, filling up to the outer ear. The silicone then hardens while in the ear, which takes about five minutes. Then Shepard will remove it and ship the model to a company that will make the custom ear protection.
If Shepard uses the 3-D scanner, he’ll take a probe and guide it through the inner ear, getting to the second bend. Along the way, he’ll map the ear so a custom earplug can be made from the scan. NAWCAD spent seven years testing different scanners to determine which one would be the best for creating custom ear protection, making sure it would offer the same protection as those created from silicone models.
“In this project we’re looking more at [whether] 3-D scanned, printed plugs and manufacturers perform as well as physical impressions. And with the technology we’re looking to transition, they absolutely do and with less variance so they’re more consistent and more reliable across subjects, which is fantastic and always something we look for,” he said.
While the services do currently use custom ear protection, production is bottlenecked by the number of audiologists who can make the silicone models, Shepard said. The 3-D scanner option potentially could be used by more people with training, he added. What 3-D scanning offers is a chance to reduce time, he said. While there is no difference in performance between an earplug made from the silicone model versus the scanner, the silicone model takes about 30 minutes while the scanning takes 10. Add in the fact that the silicone model needs to be mailed while the scanner can send the data electronically, and the scanning process takes a significantly shorter time, Shepard said.
NAWCAD also is hoping to incorporate 3-D printing, using printers currently used by military dentists to produce the customized ear protection instead of sending it to a third-party, Shepard said. “But what 3-D scanning offers with 3-D printing is the ability to start testing hybrid materials,” he said. “We really want to enhance comfort here at NAWCAD where we consider all these factors to get the best hearing protector. And comfort is one that we want to address even more.” The majority of ear protection in the forces comes in the form of a foam earplug. For one use, the foam earplug makes more sense financially, Shepard said. But foam earplugs are one time use, and even at $0.10 per foam earplug, it will become more costly than the $200 custom ear protection that can last for years.
Not to mention, foam earplugs are one size fits most, Shepard said, which means that for about a third of the military, the earplugs do not fit correctly because ears are too small or too large. Custom ear protection addresses those issues. “So while we have a good system to ensure we are keeping our operators, our pilots, our warfighters as safe as possible and addressing needs as early as possible, we can still always do a better job of enhancing their ability to perform in these extreme environments,” Shepard said.
View Lt. Cmdr. Kyle Shepard Video
Article: USNI News, September 1, 2023