Monday, June 27, 2016

Say what? Hearing Protection

First let me say that I take hearing protection very serious. I have worked for many years around flightlines around the world. Jet engines produce a lot of noise! I have my hearing checked every year and you should too. If you operate machinery, chain saws, or are around lots of noise (like shooting) please consider protecting your hearing. It has been said that 1 in every 10 Americans have hearing loss that affects their ability to understand normal speech. Hearing loss is annoying and difficult to live with. Use proper hearing protection when you shoot a firearm. Shooting is loud enough to cause permanent hearing loss.
Sound levels are represented in decibels, the increase in sound intensity is expressed in a logarithmic scale. The softest audible sound—near total silence—is represented as 0 dB. A sound 10 times more powerful is 10 dB. A sound 100 times more powerful than near total silence is 20 dB. A sound 1,000 times more powerful than near total silence is 30 dB. This means a change in volume from 150 dB to 140 dB is a more significant reduction in noise intensity than reducing 50 dB to 40 dB.
To better understand how effective protection is, it’s best to reduce its NR rating by 50% and then subtract that number from the decibel level you’ll be working around. For example, if you’re practicing with a .22-calibre rifle that fires off at 140dB and you’re using earplugs with an NR rating of 32, your equation will look like this…
32dB / 2 = 16dB
140dB – 16dB = 124dB
124dB = A much safer sound for your ears.
It’s easy to remember: higher ratings mean less noise.
To clarify how loud a sound measured in decibels can be, it’s helpful to have some everyday sound comparisons to work with. Normal conversation occurs at 60 dB. Lawn mowers run at 90 dB, a jet engine at 140 dB, and the noise on a rocket pad during launch pushes the top end of the scale at 180 dB. So where does gunfire land in the lineup? When a gun goes off, the report slams into bare eardrums at 140 dB or more. Some don’t believe a gun is as loud as a jet engine. The difference is duration. They are about the same intensity, but a gun report lasts a fraction of a second.
So what level of sound intensity is too loud for the human ear? Most experts agree you would have to be exposed to eight continuous hours of noise at 85 dB to cause permanent hearing loss, but sound spikes of 130 dB or more can cause permanent damage instantly.
The answer is ear muffs or ear plugs. Many years ago I worked on a flightline that had T37 aircraft. The T-37 has a very high pitch whine in its engine sound. It would be close to 138 dB. It wasn’t the intensity of this aircraft, it was the pitch! We would wear ear plugs AND earmuffs!
So what should you look for in your ear protection? The NRR (noise reduction rate) on the packaging should read 21 dB to 30 dB.
But if guns make 140 dB of noise, how is a 30 dB plug going to help? First, the noise tends to travel forward of the muzzle, so the shooter’s ears are not always hit by as much noise as the gun produces. This does not mean the level of sound is safe, only reduced. Second, the purpose of hearing protection devices is not to eliminate sound, but to reduce the impact to a level that does not cause lasting damage. In short, a plethora of scientific studies conducted over many years show hearing protection works, and it works at the sound-muffling levels common devices provide.
With hearing protection so high on the must-have list these days, most shooting ranges will have some form of hearing protection on hand for their customers. Hardware stores and gun stores also have a variety of options in stock. The cheapest form of hearing protection at pennies apiece are the disposable foam earplugs, which usually provide somewhere between 25-31 dB of hearing protection. Reusable rubber-type plugs are also available.
The next step up from ear plugs are the ear-protecting muffs, which have the advantage of being reusable for years. The basic clamp-over-the-ear units provide the same 25-31 dB levels of hearing protection as the foam plugs. A popular option in really noisy areas like the indoor ranges is to use both plugs and muffs. This is a good idea, but understand the limitations of this system. A 30 dB plug and a 30 dB muff together do not provide a cumulative 60 dB of hearing protection. Instead, they each act as a separate barrier the sound must travel through successively. Hearing protection is improved, but not to as high a level as one might think.
Finally, there are electronically-enhanced hearing protection devices, including specialized hearing aid/earplug combinations, and earmuffs fitted with external microphones and internal speakers. The sound system in electronic muffs allows the user to hear surrounding sounds at normal levels, or even louder than normal. When a dangerously loud sound is detected by the electronics, the speakers to the ears are deactivated until the noise reaches a safe level again. These, of course, are more expensive than conventional muffs and plugs.
Hearing protection devices, such as earplugs, should be seen as a safety standard when shooting. So it’s best to find some that fit well, otherwise you might end up missing the mark in more ways than one. It is worth it to pay a few more bucks to get the best hearing protection for shooting as possible, for both your comfort and safety.
Semper Paratus
Check 6