Long-term hearing damage is a real threat to motorcyclists, and I recently spent some time on the phone with Etymotic audiologist Dr. Patty Johnson AuD to discuss the best ways to protect our hearing. During our conversation, I unleashed the full spectrum of questions I'd cooked up during years spent riding motorcycles and worrying about my ears.
Background photo by Juanjo Viagran
The initial motivation for me to contact an audio expert, however, wasn't motorcycle-related. I'd been researching in-ear—rather than over-the ear—aviation headsets, and had read on an aviation forum that even if in-ear headsets sound quiet, vibrations from sound waves can travel through the bones around your ears and still cause damage. So that's where I started the interview.
RideApart: During some research, I read that it’s possible to sustain hearing damage even if you’re wearing earplugs. This is apparently because noise can travel through bones, which can damage your ears—even if a noise doesn’t perceptibly seem loud to you at the time. Is that true?
Dr. Johnson: That depends. If a sound is loud enough, yes, you can damage your hearing even while wearing earplugs. One of the best examples is people who work on an aircraft carrier, where the levels are really high—150 - 160 dB. People working there are using foam earplugs inserted deeply plus earmuffs. Even with that double protection, the exposure is so high that if they really want to limit risk, they have to limit time in the environment.
Sound is energy and is a wave. It’s pushing on your body, not just your ear. It does get transmitted through the skull at that high a level. If you had maximum protection—no ear canal at all—that would protect your inner ear by about 60dB. If the sound is 160 dB and you had no outer ear at all, then 100 dB would get to your inner ear. Aircraft carriers, IEDs, and gunfire are extraordinarily loud. There are some sounds that are so loud that you cannot prevent damage with just hearing protection, again, you also have to limit exposure time.
My Thoughts: The Etymotics' Noise Exposure Chart got me thinking. How can it be that you can safely listen to a chainsaw for only one minute each week—for a total of 520 minutes over a 1-decade period—but not for, say, 520 minutes in a row?
RideApart: Your hearing chart suggests that hearing damage isn’t cumulative if you limit exposure to a certain amount, and that ears can heal from day to day. Is that the case?
Dr. Johnson: Yes. I think what you’re getting at is how the damage occurs. When you have a big percussive shockwave that hits your ear like an explosion, it is possible to rupture the eardrum. Behind the eardrum is the middle ear. It has three little bones that pass the vibration onto the inner ear. In an explosion, they can become disarticulated. The wave is so strong that it permanently damages the stereocilia in the inner ear, and they cannot recover.
The situation you’re referring to is a situation of metabolic exhaustion or overload. The inner ear, like any organ in our body, requires nutrients to function. When we’re exposed to high-level of sound of over long durations, the ear uses up nutrients that are in the fluid in the inner ear. The hair cells—the stereocilia—kind of lay down. If you give the ear rest—quiet—the ear can recharge and recover, and the hair cells stand back up. Ears ring after a loud sound exposure, and that’s because you did some temporary damage and the sterocilia layed down. After a period of rest, they recover and stand upright. That’s the metabolic story.
But there’s another piece of the story that has been coming out recently, from researchers doing work on animals. I’m most familiar with a study by Dr. Kujawa and Dr. Liberman at Harvard. They gave animals a noise dose that causes temporary hearing loss. What they find is that after the animals have recovered, the stereocilia go back up, and the hearing levels recover. When they dissect the animals’ inner ears later, however, they see damage to the nerve fibers that go from the stereocilia to the brain. There is a swelling at the base of the hair cell and the nerve fiber deteriorates and detaches from the hair cell. While the ear may have mechanically recovered, there is a loss off transmission of some of the sound to the brain. It is subtle, but is progressive over time. Dr. Kujawa and Dr. Liberman think is that there is damage is beyond the level of the inner ear and it progresses over time. We first start to notice it when we have trouble hearing people in a noisy place—because of the damaged nerve fibers.
As an audiologist, this work has completely changed the way I look at noise-induced hearing loss. We used to think that temporary hearing changes were just temporary. The animal models suggest that there are other things going on that we can’t measure, and mean that it is important that we protect our hearing even from “temporary” damage.
Continue Reading: Motorcycle Hearing Protection >>
RideApart: People shop for earplugs based on Noise Reduction Ratings. But, can that be misleading?
Dr. Johnson: Yes. The NRR was the EPA’s attempt to make earplug selection easier for industry. Since it was put into law in the 1970’s, lots of research has show that the NRR doesn’t always correlate to the attenuation real users actually get. Sometimes they get a lot more, sometimes they get a lot less.
The NRR is really not helpful—at all—in terms of earplug selection, because it’s just not accurate in the real world. Motorcyclist at low speeds in an urban environment really need to be aware of what is going around them—so earplugs might dull environmental awareness. On the highway, the wind noise can exceed 100dB. At that point, you need hearing protection. Not every type of earplug works well with a helmet. Unlike foam earplugs, our 20dB ETY Plugs don’t block out more high-frequency tones than low-frequency tones. Wind and road noise are low frequency, while voices and turn signal sounds are high-frequency—which you want to hear. On a long ride, the wind noise is fatiguing. The ETY Plugs have a stem that sticks out from your ear, and so they are better suited for half-helmets.
For a full-face helmet, you want a custom musician’s earplug which will fit your ear exactly and can be had with up to 25 dB attenuation. They’re about $150 a pair, but if you’re an avid rider, it can be an inexpensive solution to feel better at the end of a ride by avoiding hearing fatigue and tinnitus.
My Thoughts: Sometimes foam earplugs block out nearly all the sound and you can blast down the highway and it almost feels like you're inside a car. The next day, on the same bike, with a new set of the same earplugs, and at the same speed, the wind is unbearably noisy.
RideApart: With foam earplugs, sometimes we get a great seal and can barely hear the wind at speed, and other times we barely notice any attenuation—even with the same earplugs. In terms of consistent sealing, how do foam earplugs compare to your ETY Plugs and custom musician’s earplugs?
Dr. Johnson: With the foam earplugs, there is more user skill to getting them in correctly. You have to roll them down tightly between your fingers, pull up and back on the top of your ear to straighten your ear canal. Then insert the plug really far and hold it in while it expands. If it is not in quite right you have to do the whole process again. I find the firmer foam plugs much easier to get in—they don’t expand as quickly so it’s easier to get them in, and when they do expand they give a better seal.
There are studies that look at the difference between what protection people are getting and what they should be getting for a given earplug. Our ETY Plugs had the least difference—which means that people were able to put them in correctly consistently. Custom earplugs can also be a really good option for a lot of people, because they only go in one way—they’re made to fit your ear exactly. Once you learn to put them in, you will have a good seal.
RideApart: Have you heard of people using water or Vaseline on foam earplugs to improve the seal?
Dr. Johnson: No, not on foam earplugs. On custom earplugs, we advise use of a water-based lubricant. That’s what we usually recommend.
RideApart: Can earplugs push earwax into your ears?
Dr. Johnson: Some people make more wax than other people. People usually know if they’re big wax producers. In that case, they should probably have their ears cleaned by an audiologist or a physician. When putting an earplug in, it is possible to push the wax in deeper. People would notice a feeling of fullness, reduced hearing, or a full-feeling ear.
My Thoughts: On RideApart, I've mentioned that the ultimate in on-bike sound management is custom-moulded, sound-attenuating earbuds, but I haven't tried that setup yet.
RideApart: Can your musician’s earplugs be had with a speaker inside?
Dr. Johnson: Etymotics doesn’t make custom in-ear monitors, but they are available from Sensaphonics.
RideApart: What do you recommend for someone who is thinking about hearing protection for the first time?
Dr. Johnson: I’m one to recommend starting at step one. If you’re not wearing a helmet, start with ETY Plugs. They’ll block the wind noise while allowing you to hear the things you need to hear. . For full-face helmets, start with foam earplugs—they’ll fit under any helmet and are a low-cost way to start. If you start using them a lot, it’s worth investing in the custom musician’s plugs that you can wear under a helmet. If you’re riding regularly, the right hearing protection can really add to your enjoyment, and it’s worth investing in a custom product.
Learn more about local earplug laws here.
How do you protect your hearing while riding? What products work best for you? Are you concerned about, or have you suffered any hearing loss as a result of riding?