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46 Law Enforcement Technology June 2014 www.officer.com TA L K I N G P O I N T S T he U. S. Army Center for Health Promotion and Preventive Medicine lists hearing loss from gunfire as the most common injury for soldiers, and the Department of Veteran Affairs says hearing damage is the number one disability claimed by returning vets. In addition, a study from the Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan, found that even with double ear protection, hearing loss still occurred in about 75 percent of those studied. It's not melodramatic or overblown to claim hearing loss is disabling some of our most brave men and women. Why is this such a problem? Everyone who has ever taken a gun to a range, either as a professional or amateur, knows you need to wear ear protection. However, research shows there could be more to protecting your hearing than just wearing the ear muffs or inserting the plugs (or both). First, how is hearing loss defined, and how does it happen? The intensity or volume of sound is measured in decibels (dB). Without going into too much detail about decibels, understand that a whisper is about 30 dB, normal conversa- tion would be 60 dB, an alarm clocks hit about 80 dB, and anything over 85 dB for an extended period of time can lead to permanent hearing damage. Over 140 dB for an impulse sound will do the same thing. Almost all firearms (pistols, rifles, shotguns, etc.) start at 140 dB and can increase dramatically from there. This is why protec- tion is so important. From the first shot fired you are already at the threshold that causes permanent, irreparable hearing loss. All standard hearing protective devices on the market have a noise reduction rating (NRR). This number is not a one-to- one ratio, meaning a set of ear muffs with an NRR of 30 does not actually lower sound by 30 dB. You have to subtract 7 from the NRR and divide by 2. So a device with NRR 30 is actually only about a 12 dB deduction (30-7/2=11.5). If you are doubling up on both ear plugs and ear muffs, add 5 to the protection with the highest rating. Now go grab whatever hearing protec- tion you've been using. Do the math; sub- tract that number from 140. Is it below 80? If not then you're damaging your hearing. But wait. You say, 140 dB is only for impact noises. I only shoot for a few min- utes at a time, so my number is 80 dB. I say, nice try. If you're in an environment where shooting is happening (shooting range, military situation, etc.) then you need to count all the time you're there. Concussive force: the silent variable in hearing loss A ten-year study on police found that even with double ear protection, hearing loss still occurred in about 75 percent of cases By Sean Bell & Sergie A. Albino A D V A N C E M E N T S I N T E C H N O L O G Y Almost all firearms (pistols, rifles, shotguns, etc.) start at 140 dB and can increase dramatically from there. This is why protection is so important. Unlike the average shooter, military and law enforcement personnel are far more likely to be involved in close-quarters combat. LET_46-49_TalkingPoints0614 2.indd 46 5/20/14 1:49 PM