I heard Randy Newberg mention in one of his recent videos that he relies on his cameramen to hear location bugles. Since the whistle of an elk’s location bugle is centered around 2 kHz (1), I started to wonder about his hearing and how many other hunters might miss bugles this fall due to hearing loss.

As an audiologist at Mayo Clinic, I work with patients who have hearing loss every day, many of them with long histories of shooting guns without hearing protection. Sometimes discussions on hearing protection are met with “well, it’s only a few shots a year” or “the muffled hearing and ringing goes away eventually.” On the other hand, my hearing aid and cochlear implant patients tell a different story – “I wish I would have known. We just didn’t think about hearing protection back then” or “I make my grandkids wear hearing protection every time they shoot. It’s just not worth it.”

My goal with this article is not to lecture about wearing hearing protection. Rather, I hope to help you appreciate the intricate work of the delicate inner ear structures, understand how they are damaged due to noise, and consider different hearing protection options. In the world of noise-induced hearing loss, “an ounce of prevention is worth more than a pound of cure.”

Fair warning – some parts get technical, so feel free to skip around using the headings.

UNDERSTANDING HEARING: HOW DOES HEARING WORK?

The ear is composed of three major parts – the outer, middle, and the snail-shaped inner ear as shown in Figure 1. The outer and middle ear pick up the vibrations of sound and deliver them to the hearing part of the inner ear called the cochlea. Along a membrane in the inner ear, 16,000 tiny hair cells turn the vibration of sound into nerve signals that are sent to the brain. These hair cells are embedded in the inner ear membrane, and each hair cell has dozens of stereocilia on top which are shown in Figure 2. (2)

These sensory hair cells play an essential role in hearing, and they are one of the structures that can be permanently damaged due to noise exposure, causing hearing loss. High levels of sound can cause the stereocilia to bend, break, and trigger the underlying hair cell to die, turning into scar tissue. (3) See Figure 3 below for a visualization of hair cell damage.

UNDERSTANDING SOUND LEVELS

When talking about sound level, we use exponential units called decibels. Normal human hearing has a spectacular range from soft to loud, and decibels allow us to talk about sound level with manageable numbers. For example, a car horn from 16 feet away is approximately 100 dBA, which is a billion times more powerful than the level of normal breathing at ~10 dBA. Every 3 dB increase represents a doubling in the overall energy of sound, so seemingly small numeric changes represent big changes in the amount of sound. (4)

CONTINUOUS NOISE VERSUS IMPLUSE NOISE

Continuous noises like chainsaws, factories, and motorcycles damage our hearing differently than impulse noises like gunshots. (5) Think of continuous noises overworking the ears while impulse noises overdrive the ear’s limits. Because of this, they require different standards for safe listening levels.

HOW LOUD IS TOO LOUD?

OSHA provides different standards for continuous and impulses noises. See Figure 4 below for sound examples at different levels and the associated OSHA standard. (4,6-9)

According to OSHA guidelines for continuous noise, a person can safely be around 90 dBA for a maximum of 8 hours, whereas it is only safe to be exposed to 110 dBA for a maximum of 30 minutes (6). Think of noise exposure as a daily dose of sound – loudness and duration of sound contribute to this dose. Workers from noisy industries might be familiar with the 85 dBA cutoff for continuous noise, above which OSHA requires hearing protection.

For transient sounds such as gunshots, OSHA sets 140 dB peak as the maximum allowable level. (7) They do not put a limit on the number of impulse noises as long as they are less than 140 dB peak. Because impulse noise damages hearing by overdriving the ears, dB peak is used to capture the total amplitude or height of the impulse. This is distinct from dBA, which captures the overall level of the continuous sound.

HOW LOUD IS MY GUN?

Too loud, with rare exceptions. Even .22 LRs are 140 dB peak. Moving up from there, a .30-06 is about 160 dB peak. The Counsel of Accreditation in Occupational Hearing Conservation provides a fairly comprehensive list of different firearms and their sound levels. Measuring impulse noises accurately requires special equipment that can handle the extremely high levels of sound without distortion. Although sound level meter apps on your phone can accurately estimate some continuous noise levels, they cannot handle impulse noises such as gunshots. (10)

Gun-related variables that impact the loudness of your rifle are loads, suppressors, and brakes. Cal Zant at Precision Rifle Blog wrote a comprehensive article on this, which is where the figure below comes from. (11) The noise reduction that suppressors provide is excellent, but the financial and legal hurdles to obtain them are prohibitive for many hunters.

The environment in which you are shooting will affect how loud the firearm is. Enclosed spaces like indoor ranges, goose pits, and enclosed blinds will result in louder, more harmful sound levels due to Boyle’s law. The same gun in a smaller area results in louder, more damaging sound levels.

“IT’S ONLY A FEW SHOTS A SEASON AND MY HEARING ALWAYS COMES BACK…”

I often hear from my patients that they wear hearing protection on the range but not when hunting due to the inconvenience. I will then ask if they experience ringing in the ears or muffled hearing following their shots, which is almost unanimously the case. Since hearing has come back and the ringing subsided, it gets shrugged off as not a big deal, but these changes are signaling permanent damage to the inner ear.

It is true that the ringing can subside, and the hearing loss can recover. This is called temporary hearing loss or technically a “temporary threshold shift.” These changes in hearing can take up to thirty days to recover. The time of recovery typically correlates to how much damage has been done – more damage requires more time. Beyond 30 days, the changes are permanent. (12)

Even if hearing completely recovers on the hearing test, Drs. Liberman and Kujawa at Harvard found underlying damage to the junction between the sensory hair cell and the nerve of hearing. (13) This “hidden hearing loss” causes difficulty hearing in background noise and sets the stage for hearing loss in the future, especially if the noise exposure continues. (14)

Even if hearing seems fine following a temporary hearing loss, there is still damage happening to the inner ear. There is truly no escaping the hearing damage resulting from gunfire.

UNDERSTANDING AND APPLYING NOISE REDUCTION RATING (NRR)

“Okay, so my gun is ~150 dB peak, and my earplugs have an NRR of 20 dB. I’m good, right?”

…maybe.  OSHA suggests the following calculation to estimate noise exposure reduction: (NRR – 7)*0.5. So the 20 dB NRR earplugs are conservatively giving (20-7)*0.5 = 6.5 dB of attenuation. In the instance of a 150 dB Peak gun, that’s not enough. The reason OSHA recommends the “derating” factor of 50% is because of widespread improper use or fit. So, if you have the properly sized earplugs and get them seated correctly, you might be just fine. This is a reason to consider custom earplugs.

If you double up on hearing protection, the recommended formula is: [(NRR of higher value – 7)*0.5]+5. So earplugs with a 20 NRR used in combination with an earmuff with an NRR of 30 would yield [(30-7)*0.5]+5 = 16.5 dB. Using hearing protection properly is crucial, and that starts with selecting the right devices for your ears.

HEARING PROTECTION: OPTIONS, OPTIONS… EARPLUGS, EARMUFFS, CUSTOM, AND ACTIVE
EARPLUGS

An earplug can be a very effective option if sized, placed, and occluding the ear canal properly. When I place insert earphones for hearing testing, patients will often comment on how effective my earplugs are. Really, they are the same thing you can get at a big box store – I am just placing them far enough in the ear canals for them to work. To properly place earplugs, I recommend the “Roll, Pull, Hold” method that is shown in the picture below.

Since everyone’s ear canals are different sizes and shapes, earplugs might simply not be a good option for your ears. If your ear canals are too small or too curvy, you might not get them placed deeply enough. If your ear canals are too big, the earplug might not fill the entire canal and as a consequence, not adequately protect hearing. The flange shaped plugs that look like Christmas trees can work well in the right ear canal, but they are prone to leaving openings around the edges of the plug, again not adequately protecting hearing.

EARMUFFS

Earmuffs are easier to use properly and can provide high NRRs. Put ‘em on and good to go. While earmuffs offer excellent sound protection, they can be heavy, clunky, hot, and get displaced when shouldering a gun. Personally, I will use earmuffs at the range, but I do not like them in the field for those reasons, which rings true for many hunters.

CUSTOM EARPLUGS

To avoid the drawbacks of earplugs and earmuffs, I recommend moving to custom earplugs. They provide a consistent fit with immediate protection, and they are typically more comfortable for long-term use. Custom earplugs are lighter, less clunky, and manage temperature better than earmuffs. They cost around $150-$200 but are well worth the one-time expense in my opinion. Custom products require impressions to be made, and I would recommend this be done professionally. Click here to find a certified local audiologist.

ACTIVE HEARING PROTECTION

Active hearing protection is a great option to maintain sound awareness and still protect hearing. This technology has expanded beyond the active earmuff options, with active earplug options being more widely available and affordable. Studies have shown that active earmuffs and plugs provide adequate protection for firearms. (17) They work well for situations when there is no shot anticipation – upland birds, waterfowl, drives for deer, etc. I have had a great experience with my custom active hearing protection from Starkey Sound Gear. I used them on a week-long goose hunt in Canada with six other guys (there was a lot of shooting), and I use them on my pheasant hunts every year. My biggest complaints are that walking through grass seems too loud, the wind noise can be annoying at times, and getting the volume set perfectly can be a chore. Despite these minor annoyances, I have not had hearing problems, and I test my hearing daily to check my equipment at work.

The active earmuff style is the cheapest option (~$40). Sound Gear has both a tree-style, in-the-ear plug ($400 a pair), and a behind-the-ear style with a tube that connects to a foam plug ($179 a pair). Provided they have suitable ear canals, I recommend these for patients who don’t want to spring for active, custom options ($1k+) but want to do something to protect their ears and still hear while hunting.

Other brands offering active hearing protection include Westone, Otto, ESP, Walker, Etymotic, 3M, and more. Feel free to chime in with your brand and experience in the comments. I chose Sound Gear because Starkey is a reputable hearing aid company with a good understanding of both sound processing and the mechanics of hearing. They were also the most cost-effective.

WRAP UP

Unfortunately, there is no cure for noise-induced hearing loss. My job is to help people hear better with hearing aids and cochlear implants, but if you ask my patients, they will verify that hearing with these devices does not compete with normal, natural hearing.

There is no denying that wearing hearing protection is a hassle, but the inconvenience of wearing something a few days a year can prevent having to wear hearing aids or cochlear implants all day, every day later in life. There is an assortment of hearing protection devices on the market, and I hope the discussion above helps you narrow in on what might work for you.

As a novice backpack hunter, I have learned many tips and tricks from Randy Newberg. His reliance on cameramen to hear bugles demonstrates the importance of preserving long-term hearing. Protecting your hearing from noise exposure today will help you hear bugles until your last hunt.

You can comment on this article or ask Weston questions here.

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  2. Schwander, M., Kachar, B., & Müller, U. (2010). The cell biology of hearing. The Journal of Cell Biology, 190(1), 9-20. doi:10.1083/jcb.201001138
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  4. What Noises Cause Hearing Loss? (2019, October 07). Retrieved September 19, 2020, from https://www.cdc.gov/nceh/hearing_loss/what_noises_cause_hearing_loss.html
  5. Wada, T., Sano, H., Nishio, S., Kitoh, R., Ikezono, T., Iwasaki, S., . . . Usami, S. (2017). Differences between acoustic trauma and other types of acute noise-induced hearing loss in terms of treatment and hearing prognosis. Acta Oto-Laryngologica, 137(Sup565). doi:10.1080/00016489.2017.1297899
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  9. Occupational Safety and Health Administration. (n.d.). How Loud is Too Loud?  Retrieved September 19, 2020, from https://www.osha.gov/SLTC/noisehearingconservation/loud.html
  10. Murphy, E., & King, E. A. (2016). Testing the accuracy of smartphones and sound level meter applications for measuring environmental noise. Applied Acoustics, 106, 16-22. doi:10.1016/j.apacoust.2015.12.012
  11. Zant, C. (2018, December 23). Muzzle Brakes: Sound Test. Retrieved September 19, 2020, from https://precisionrifleblog.com/2015/08/07/muzzle-brakes-sound-test/
  12. Ryan, A. F., Kujawa, S. G., Hammill, T., Prell, C. L., & Kil, J. (2016). Temporary and Permanent Noise-induced Threshold Shifts. Otology & Neurotology, 37(8). doi:10.1097/mao.0000000000001071
  13. Kujawa, S. G., & Liberman, M. C. (2015). Synaptopathy in the noise-exposed and aging cochlea: Primary neural degeneration in acquired sensorineural hearing loss. Hearing Research, 330, 191-199. doi:10.1016/j.heares.2015.02.009
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