EOD demonstration measures impact level of explosive noise Published Sept. 21, 2012 By Jenny Gordon Robins Public Affairs ROBINS AIR FORCE BASE, Ga. -- It's a team effort to ensure members of the 116th Air Control Wing's Explosive Ordnance Disposal Flight are being protected when it comes to their hearing. Since they are regularly exposed to explosives being set off as part of exercises conducted on a base proficiency training range, it's important to measure what the effect is from each detonation. An explosives demonstration was conducted Wednesday on the range, where a small, yet very powerful, number were on hand. This included a half pound of Symtex, a general-purpose plastic explosive, a pound and a half of TNT, a stick of dynamite and a blasting cap (the size of a pencil eraser) contained in an 8-ounce plastic bottle. Standing about 600 feet away, as each explosive was detonated, a device was held to a detonator's ear, measuring noise exposure, specifically impulse noise. "The reason we measure noise in general is to make sure we're protecting people as much as possible from further hearing loss," said Capt. Erin Artz with the 78th Aerospace Medicine Squadron's Hearing Conservation Clinic. "Especially with 'impulse' noise, it's a different type of noise than what we're used to measuring." "With EOD it's a bit different," she continued. "A couple of impulse noises at close range, and very intense, can damage your hearing permanently. It's important we get a good foundation of a measurement and also what kind of noise they're exposed to on a regular basis." As opposed to constant noise that can occur in industrial areas for example, impulse noise can make the body react differently. "With an exercise like this it's important because it allows EOD to showcase their capabilities, and also allows us to take good, real-world readings," said Staff Sgt. Barham Bratton, 78th AMDS bioenvironmental engineering craftsman. An annual hearing test is conducted on Airmen exposed to hazardous noise based on these readings taken. Then based on those measurements, any engineering, administrative or personal protective equipment controls are recommended. "That way we can monitor to see if the readings we've taken are accurate, to see if they're being exposed to more noise than is healthy to maintain their hearing," said Artz. Different explosives create different burn rates, explained Tech. Sgt. Barry Duffield, a 116th ACW Civil Engineer Squadron EOD Flight team leader. "Every explosive takes a certain amount of heat shock or friction to get a detonation to occur. Some take more than others," he said. "On the principle of detonations, you start out with a small amount of sensitive explosives, and amplify that explosive wave to your main charge." For example, as Symtex and TNT were exploded in the distance, its effect resulted in a large, resounding blast. "There's maybe a real subtle different with the sound of these," said Duffield. "With Symtex, there's more of a crack to it, where TNT has more of a push. They have different purposes so they'll have different reactions." A single blasting cap ended the demonstration. Although it had the smallest blast, it still shredded the plastic bottle it was enclosed in. "They're a very powerful and a very sensitive explosive," said Duffield. "If you had it in your hand, you may have a stump."