By Chuck Hawks
Hearing protection is an important but often neglected subject, particularly by new shooters. The younger and less experienced the shooter, the less attention they seem to pay to protecting their hearing. It's the old timers, who have already lost a substantial amount of their hearing, who are most likely to wear adequate ear protection while shooting. Having achieved geezerhood, and being half-deaf after a lifetime of shooting, I have learned the hard way that hearing protection is mandatory.
Any type of ear protection is designed to reduce the sound pressure level (spl) that enters the wearer's ear canal. Sound pressure level is measured in decibels (dB). According to the American Heritage Dictionary, the definition of decibel is as follows: "A unit used to express relative difference in power or intensity, usually between two acoustic or electric signals, equal to ten times the common logarithm of the ratio of the two levels."
The bottom line is that the decibel scale is not linear. The amplitude of the sound pressure wave actually doubles with every 3 dB increase. For example, a 93 dB spl is twice as loud as a 90 dB spl. Or an ear protector that reduces the spl by 27 dB is actually twice as effective as one that reduces the spl by 24 dB. So what sounds like a relatively small numerical change actually represents a substantial change in spl. Keep this in mind when comparing the advertised noise reduction rating (NRR) of various ear protectors.
How Loud is Loud?
Amplitude and duration are the key factors to consider. Noise becomes damaging to hearing above a certain level for a certain time, usually cited as 90 dB for 8 hours. ("A weighted"--that is weighted to conform to the frequency response curve for average human hearing.) This means that listening to music at a 90 dB spl for an hour is not considered damaging, but working in an environment with a continuous 90 dB spl for 8 hours would be.
As the amplitude goes up, the duration your ears can stand without damage goes down. At a 100 dB spl the tolerable duration drops to 2 hours. At 115 dB the duration drops to 15 minutes or less. The pain threshold is quoted at 130 dB.
My Realistic spl meter can read up to 126 dB, and when I tried to measure the loudness of centerfire rifle and handgun fire at my ear position, the blast regularly pegged the meter. I remember reading somewhere that levels of 140 dB were common from firearms. I suspect that is true, and at that level the sound is immediately damaging to hearing. Certainly it literally hurts the ears to shoot a centerfire rifle or magnum revolver unprotected, something most of us have experienced accidentally at the range when we forgot to put our hearing protectors on.
At least gunfire is of very short duration. If in fact muzzle blast achieves an spl in the area of 140 dB, then attenuating that level by 25 dB would reduce the spl to 115 dB, which can be endured for up to 15 minutes--far longer than the spike in spl caused by a single shot. If you ear protection drops that spike to 110 dB, the sound that assaults your ear is about as loud as amplified rock music, and could be tolerated for about 30 minutes. At that point your hearing is probably pretty safe.
Ear protection comes in different forms. The most common are various types of ear plugs and headphone type hearing protectors, and it is these that are discussed in this article.
From cotton balls to custom fitted ear plugs, these small devices are the least obtrusive, and probably the most common, form of hearing protection. They are surprisingly effective. Silencio, a major producer of hearing protection devices of all types, credits their disposable Red-E-Fit foam earplugs with a noise reduction of 32 dB. Their silicone, reusable Economy Earplug is rated at 26 dB, while the conformal silicone Silent Partner carries a 25 dB NRR. The Super Sound Barrier, a valve type earplug designed to allow normal conversation, only reduces the maximum spl by 7dB, however, and does not offer adequate protection from gunfire. In the field I prefer earplugs, because they are less bulky than earmuff type hearing protectors.
Earmuff Hearing Protectors
These are the common "clamshell" ear protectors that look like a pilot's headphones or stereophones. Many shooters find them more comfortable than any type of plug that must be inserted into the ear, while others find them too bulky. Personally, I prefer to wear earmuff style ear protectors.
The less expensive models usually have a foam ear cushion, while the better models have a liquid filled ear cushion. Either way, it must make a good seal against the head if the ear protection is to be fully effective. Eyeglass frames, for example, degrade the seal around the ear. One advantage of earmuffs is that in really loud situations, such as at an indoor range, ear plugs can be worn inside of the earmuffs, considerably increasing the level of protection.
Silencio offers earmuff models that offer noise reduction ratings from 22 dB to 29 dB when worn over the head. If the band is worn behind head or under the chin protection is reduced, as the ear seal is not as efficient.
The Original Earmuff has foam filled ear cushions and a NRR of 25 dB when worn over the head, 24 dB when worn behind the head, and 23 dB when worn under the chin. The similar Liquid Earmuff is an Original with liquid filled ear cushions and carries a NRR of 28 dB when worn over the head.
There are also earmuff hearing protectors that include a radio, for those who cannot stand being deprived of their tunes, even on a rifle range. The Silencio Relax Electronic is such a model and incorporates an AM/FM stereo radio in a conventional hard-shell earmuff with a NRR of 27 dB when worn over the head.
Electronic earmuffs incorporate a battery powered audio amplifier that allows normal--or better than normal--hearing. A small microphone in each muff picks up the external sounds, which are amplified and fed to a small speaker in each muff. A master volume control allows the user to control the speakers' volume. Loud sounds (in excess of 80-90 dB) are blocked by an electronic circuit that cuts off the speaker, allowing the amplified headphone to offer protection from loud noise comparable to standard clamshell ear protectors. Electronic (amplified) ear muffs are typically powered by common AAA or 9 volt batteries, although some models use rechargeable batteries.
Silencio's Falcon electronic earmuff features an 82 dB speaker cutoff and a 22 dB noise reduction rating. Their Frontline model also has an 82 dB speaker cutoff and a noise reduction rating (NRR) of 27 dB. The Rangesafe stereo earmuffs provide protection in continuous noise environments, features separate microphones, speakers, and volume controls in each ear cup, run up to 500 hours on 4-AAA batteries (2 per side), and shut down when noise levels exceed 85 dB. These Silencio units are fairly typical of electronic earmuffs.
Some electronic earmuffs include a radio mode as well as amplification of outside noises and hearing protection. The Silencio React Electronic is this type of unit. It combines the active listening of the Frontline with an AM/FM radio and provides up to 50 hours of listening on a single charge of its rechargeable nickel-metal hydride (NiMH) battery (charger included). The NRR is 27 dB when worn over the head.
Summary and Conclusion
As you can see, the various types of hearing protectors can offer relatively similar levels of protection. I find it surprising that the most expensive type (Electronic earmuffs) typically offer no more protection than cheap earplugs. Their advantages are in other areas.
I usually use disposable earplugs for temporary use (such as checking a rifle's point of impact in the field), and I keep a few sets in all of my shooting "kits" to give away to shooters who forgot their "ears." I try to wear higher quality, reusable earplugs when hunting.
When plinking or shooting by myself I tend to prefer standard earmuffs, as they are usually lighter and possibly more comfortable than the amplified type. At rifle, pistol, and trap ranges, where it may be important to hear other shooters speak, I like to wear electronic earmuffs.
In especially noisy environments, such as when shooting very loud (often magnum) firearms or at an indoor range, I think it is wise to wear earplugs inside of earmuffs. This "belt and suspenders" approach provides the maximum level of hearing protection.
Try to match the level of hearing protection to the need. But most of all, always wear some sort of ear protection when shooting.
Copyright 2005, 2013 by Chuck Hawks. All rights reserved.