Sound energy is rated on a confusing scale. Sure, you’ve probably heard of decibels. You might’ve seen a chart that describes the sound energy (“volume”) produced by various things – like a rock concert, or an aircraft engine. But what you may not realize is that your favorite handgun or rifle produces so much sound that a single shot can permanently damage your hearing. The speed that the sound of gunfire travels as is so fast, and heard so briefly, many don’t perceive it to be damaging to their hearing.
Even seasoned gun owners may not realize that to protect your hearing while shooting, you must often double up your hearing protection. That means wearing both ear plugs and a pair of over-the-ear shooting muffs. Let’s break down why this is the case, and why even firing a .22 LR a few times can cause measurable hearing damage.
How Sound is Measured
The “loudness” or volume of the noises we hear is just our way of comprehending how much energy sound produces in the air around us. Unfortunately, we’re not very good this. Sound energy does not equal loudness. And it’s not the loudness of a sound that damages our hearing, it’s the energy of the sound wave itself.
Although we can’t touch, taste, or smell it, sound is a physical phenomenon that interacts with the delicate tissues and structures in our ears. A sound’s pressure wave moves through the atmosphere, eventually imparting that energy on our ears. The greater the pressure wave, the louder we perceive the sound we hear – but it’s not a 1:1 ratio.
The energy of a sound wave is measured in decibels, or “dB”. Importantly, decibels are not linear, and they do not measure loudness. They measure energy. A 1 dB increase in sound does not merely increase the energy of that sound by 1%. In fact, just 1 decibel of extra sound translates into 26% more sound energy. A 3 dB increase yields a 100% increase in energy, but we our ears can only perceive that doubling of energy as a 23% increase in volume, or loudness.
That’s why sound – particularly fast, brief sound – can be so dangerous: Although we can clearly perceive one sound to be louder than the other, we cannot perceive that such a sound might be twice as powerful. What’s more, even incredibly brief but powerful sound waves can cause some serious hearing damage – even if that sound didn’t last long enough for our ears and brains to perceive it as painful.
Why Wearing Ear Pro While Shooting is so Important
Unsuppressed gunfire produces some of the most energetic, fastest, and briefest sound waves imaginable. Because these sounds travel so quickly – and because our ears only perceive the audible noise for such a short period of time – we may not realize we’re damaging our hearing with every pull of the trigger.
What’s more, even the weakest, slowest firearm cartridges produce enough sound energy to cause permanent hearing damage with just one or two gunshots. It’s generally accepted that any noise above 120 dB, no matter how brief, can cause immediate hearing damage. But one of the smallest, least energetic rifle cartridges, the .22 LR, can produce up to 155 decibels of sound energy.
Even suppressed gunfire can cause hearing damage without worn ear protection: a suppressed 9mm handgun cartridge produces around 126 dB of sound energy. Some of the most popular and commonly chambered cartridges – like .308 Winchester and 5.56 NATO – produce energy in excess of 165 to 170 decibels.
Adequate hearing protection is the only way to mitigate the threat of hearing damage caused by firearm cartridges. But because these cartridges produce so much energy, wearing just one layer of protection may not be enough.
How to Calculate the Hearing Protection You Need
Remember that 120 dB – the level of sound energy that can cause hearing loss with any length of exposure time – is the number we need to beat. That means the hearing protection we wear while shooting must reduce that dangerous sound energy of gunfire to below 120 dB.
When it comes to obtaining this level of protection, you have two choices: ear plugs, and earmuffs. It’s best to invest specifically in ear muffs for shooting. Both types of “ear pro” generally provide noise-reduction ratings (NRRs) of between 22 and 34 decibels each. Shooting muffs provide a better, more comfortable fit – but remember, you’ll often need to double up on hearing protection to obtain the right noise reduction rating.
OSHA, the agency tasked with regulating safety standards and equipment, says that the “real world” rating of hearing protection is often less than the advertised NRR. That’s because while NRRs are obtained in lab testing, users often fail to obtain a proper seal around the ear. Sound may also be heard at closer distances – especially when shooting a firearm – thus increasing the decibels produced.
Passive vs. Active Hearing Protection
Doubling up on ear plugs and shooting muffs will certainly provide the protection you need while shooting. But wearing that much ear pro also means you can’t hear what’s going on around you. That’s where active hearing protection (like electronic ear muffs) comes in.
Unlike passive ear pro – which includes standard muffs and ear plugs – active ear pro (which is battery-powered) allows ambient sound and human voice to pass through to the wearer’s ears. Most active hearing protection even amplifies this hearing-safe sound to compensate for users wearing both muffs and plugs. This is accomplished through directional microphones and sound sensors built into ear pro.
When excess sound energy is detected by the onboard sensors within the ear cups, the microphones shut off before that sound reaches the user’s ears. This happens in milliseconds or less, measured by something called “attack time.” The faster the attack time rating, the more effective the active hearing protection is at attenuating excess sound energy without a noticeable delay or interruption in the hearing-safe sounds being pumped through the device.