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 Post Posted: Wed Jul 10, 2019 9:41 pm 
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BRONZE
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Joined: Fri Aug 24, 2018 1:02 am
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Location: Longview, TX
In a recent post, there were a dew questions about hearing protection. Having spent 15 yrs or so in the field, I thought I'd add a bit of information on the subject to the forum here.

For the Hunter and/ or Shooter and anyone who is in the area of the discharge of firearms, you should wear hearing protection. Otherwise, over the years, you will loose parts of or all you hearing. Let me explain: “Normal hearing” is an average of hundreds of peoples hearing 'pure tone' tests averaged over the numerous pure tone ( sine wave ) tests. Everyone is a bit different in body build and hearing is no exception. The tests will get you close enough that one can say they have “normal hearing.” A hearing test (long form) will test you at 125 Hz, 250 Hz, 500 Hz, 750 Hz, 1,000 Hz, 1,500 Hz, 2,000 Hz, 4,000 Hz, and 6,000 Hz. A person with “good ears” can hear (detect) sounds from 20 Hz to as high as 20,000; however, most folks drop out at or above 10,000 Hz ~ 12,000 Hz by adulthood. Humans hear best from 1,000 Hz to 4,000 Hz. (The majority of human made sounds in this band would be crying babies.) Human speech runs from 500 Hz to near 1,200 Hz, Speech intelligibility, the ability to tell the words “time” and “dime” apart (and other 'close' words) runs from around 500 Hz to near 2,000 Hz.

We measure “sound” in decibels, dB. A 3 dB change in sound is double the power or one half the power. If you listen closely, you can just barely hear the loudness difference in a 3 dB change. (The old '60's and '70's home stereo volume controls that had the detentes or clicks as you turned the volume up or down were supposed to be 3 dB power changes.) In audio, in relation to the ear, we use an A weighted dB scale that approximates A spoken whisper is in the 50 dB range. A conversation is around 70 dB. A book hitting the floor on it's side or a balloon “pop” is around 80 dB. ( In the USA, the gov agency, OSHA, requires hearing protection for workers who are exposed to 85+ dB workplace noise.) A Sony “Walkman” turned all the way up can exceed 90 dB. A very loud dance floor is almost 100 dB. Between 110 and 120 dB, you will reach the threshold of actual pain. A 12 gauge shotgun, 5 feet from the side of the muzzle, muzzle blast will make several peaks at 150 db. ( I actually did a research and documentation on this once.) A center fire rifle will develop muzzle blast from faster burning powder from a smaller diameter bore than a 12 ga shotgun, so I would assume a higher dB level muzzle blast with higher frequencies.

Humans with about equal hearing in both ears have a good horizontal sound location ability. If there's a sizable difference between ears' abilities, this ability is diminished. Hearing, simplified, is the Outer ear directing sound into the ear canal which causes the eardrum to vibrate. The vibrating eardrum in turn vibrates the 3 bones of the inner ear that form a mechanical amplifier that presses on the Cochlea. The cochlea is a 'closed system' which is like a spiraling organ filled with liquid with hairs inside. ( When I studied this, there was no was to open a cochlea up to actually confirm how it operates. However, the following was the assumed theory of operation from the '90's.) The last bone passed the vibrations to the cochlea. The entire liquid volume within the cochlea passed the sound throughout the spiral. This spiral is lined with minute hairs standing up into the fluid. It was thought that different areas of the “hairs” were associated to different frequencies. The base of each hair has a nerve which transmits to the Auditory nerve which transfers the signals to the brain to process. (Yes, it sounds like an analog to digital converter.) These “hairs can suffer temporary damage from loud or prolonged loud sounds. They can also be 'killed' ( broken off and laid flat) by extremely loud sounds.

Examples: You go to a Rock Concert and sit in front of the stage speakers, you go for an afternoon bicycle ride while listening to your favorite Death Metal Band thru headphones with the volume 'cranked up,' you go to the range to 'run' a couple of magazines, you go on a night hog hunt and find a sounder that doesn't run out of sight when you shoot. Driving afterwards you find that the car radio volume needs to be turned louder. You have suffered a 'hearing shift.' This means you have lost 10 dB of sound detection or more. This may last half a day or as long as several days before you hearing returns to normal. These types of events or more can also cause tinnitus, that ringing in the ears.

Part of my enlistment physical was a complete hearing test when I went into the Marine Corps. My chart shows that I had 'normal hearing.' After a bit of fighting in Vietnam, I took another complete hearing test when I reenlisted. While my right ear appeared unchanged, my left ear showed a 40 dB loss at 4,000 Hz and a 60 dB loss at 6,000 Hz. (I shoot a long gun right handed which placed my left ear facing more forward toward the muzzle.) The Navy doctors and the VA agree that my loss is permanent; but, it shouldn't effect my work and it's not bad enough for a hearing aid or a disability. (However, I do get a disability check now for tinnitus. My frequency loss also looks like hearing loss from a civilian job in a noisy (85+ dB, long term exposure) in a civilian factory. I know a guy who wasn't in the military and had a 'quiet' regular job. He also raises cows and bails hey for the critters. Bad mufflers on the tractors made them loud enough that he now wears hearing aids from the hearing damage from the tractor motor noise. Non-Sound related, I know people who wear hearing aids due to high temperature from a disease, x-ray treatment of the head and just growing old.

So, how does a Hunter/ Shooter avoid these hearing losses? Wear hearing protection when you shoot. There are “passive” devices that you just place in your ear. Most of these have around 30 dB reduction of sound. Looking quickly thru Academy's web sight, low end cost starts at around $3.50 for 2 pair that can be used multiple times. If you maintain your weight well, many hearing aid sales outlets can make you a custom ear mold set from $70 ~ $100 that should get closer to 40 dB . The larger ear covering cup type ear protectors drop sound around 40 dB. The costs I saw run $40~ $50. The next type are the “active” hearing protectors. These hearing protectors consist of a microphone, an amplifier, a limiter (clipping, negative feed , compression circuitry) and output amplifier and a speaker ( receiver) for one or both of the user's ears along with a couple of batteries for each side (usually AAA batteries.) The cup shaped headphones in this class usually provide about 30 dB protection when turned off. I have a pair with the “thinner” cups that are easier to use with a long gun. Each side has a rotary switch that turns that side on and sets an output level for ambient sounds to be at your preferred level. They sound like they clip anything above 85 dB; but, that might also be a fast compression. They were the next to lowest price when I bought them, about $40. There are electronic muffs available the can run up to several hundred dollars. There are devices built on the Behind-the-ear style of hearing aid bodies. These usually use a silicone rubber tube from the amplifier/ receiver in the BTE body thru an earplug in the ear to conduct the sound. The plugs fit and the tube picking up high dB sounds limit the usefulness in my opinion. A better choice would be the In-The-Ear style hearing aid body for this type of build. However, this increases the cost even more. And, if you are really rich, you can buy some of today's modern microprocessor base actual hearing aids and use them for hearing protectors.

Which is your best choice? Well, for straight hunting only, the plain old cheap earplugs are the most economical choice. If you also shoot at a range with others, then I would suggest the entry level electronic headphones for a start. I used to shoot a lot off the local club's benches and the had a lot of sound from the metal roof over the bench, But, they also allowed you to hear the “Range Hot” or “Range Cold” commands and other conversations around you better than just sound reducing devices. They are better for safety around others.

Why do you need protection ? In the 12 gauge study that I documented, I found that the shotgun blast developed one peak of 125 Hz to about 150 dB. There were 2 peaks at 250 Hz from the one shot that also peaked about 150 dB. There was a 500 Hz peak about 130 db. There were also peaks above 120 dB from 750 Hz up thru 2,000 Hz. From my military experiences in Vietnam, I used the M-60 mg with U.S. 7.63mm ball, M-16 with U.S. 5,56mm ball and an M3A1 “grease gun” in .45 ACP ball. My hearing loss in the 4,000 Hz and 6,000 Hz ranges suggests to me that the center fire long guns generate higher frequency peaks and higher levels of power. My personal untested theory is that a reduction of about 30 dB is minimal for shooting hearing protection.

With anything, you must use it appropriately. If you just use anything that plugs in the ear, make sure you insert them correctly to seal the er canal. Brands and types will vary in their abilities. A well designed 'active system' will use components to reduce unnecessary frequencies and aid the sound reduction by design if the designer understands what they are trying to accomplish. A good design accomplishes it's goals cleanly. AQ poor design may cost as much but will have loud clicks or pops. Sorry for being so long winded...

_________________
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Semper Fi,

Tom


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 Post Posted: Thu Jul 11, 2019 12:58 pm 
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BRONZE
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Joined: Tue Apr 23, 2019 9:59 pm
Posts: 116
Thanks Tom, very well written! Wish I would have known this when I was a kid shooting dove and quail. That 12 ga took a lot of my hearing on my left side.


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 Post Posted: Sun Jul 14, 2019 9:54 am 
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SILVER
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Joined: Mon Jan 29, 2018 10:50 pm
Posts: 294
My new hearing aid has a sound compression which the audiologist said probably rates to about a 25 and she did not recommend it for hunting although she said some use it for that. It's probably not sufficient for that purpose.


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