There’s a common problem faced by many law enforcement agencies. They built a shooting range in a remote area of their jurisdiction years ago. Now that remote area is a residential neighborhood and the residents are not fond of their noisy neighbors, no matter how much the cops need to train. The residents complain to the media and to the city council, and the agency has to cut back on training or find a solution.
One solution is of course to move the range. It’s not always practical, and it can be very expensive and time consuming. In order to relocate a shooting range, you have to perform lead remediation on the property where the range was previously located, acquire property for a new range, and build a new range.
A cheaper solution for many law enforcement agencies faced with a noisy range problem, the solution is to treat the range to mitigate the noise. That is the specialty of Troy Acoustics.
Noise and Time
Bill Bergiadis, founder and CEO of Brunswick, GA-based Troy Acoustics, says the noise level emanating from shooting ranges into the surrounding area and affecting officers while training is a result of several different factors and not just sound level at the muzzle of the firearm. He says, for example, the sound reflects off the walls of the range and surrounding structures.
Excessive noise can severely damage the hearing of officers who train on a noisy range, even if they wear hearing protection. And compromised hearing can be an officer safety issue. “Agencies that train on an untreated range are doing a disservice to their officers and to public safety,” Bergiadis says.
Excessive noise on a shooting range does more than irritate the neighbors or even damage the hearing of the people on the range, it can make them sick. Some ranges violate OSHA’s noise exposure limits of 85 A-weighted decibels (dBA) for over an eight-hour period. That standard is based on noise level and time of exposure. The higher the noise level, the less time you can safely train on that range. With some firearms exceeding 160 decibels at the muzzle, it doesn’t take much time to reach the OSHA limit. Bergiadis says he know of a range where it is unsafe by OSHA regulations to fire more than nine rounds per day.
Reflection and Overpressure
When a gun is fired, the noise is so loud that it reflects off of nearby structures such as walls and ceilings. On an outdoor or indoor range this noise can bounce around the area for as much as four to nine seconds.
Bergiadis says one of the goals of treating a range to mitigate noise is to reduce that reflection time, expressed as RT60, to 1.5 seconds. “The quicker that the gunfire noise is absorbed in the range, the longer you can train and the lower the risk of exceeding the OSHA limits,” Bergiadis says.
In addition to noise, there is a pressure wave when you fire a round. This overpressure can be as much as 1,500 pounds per square inch and it also reflects off of the surrounding structures, walls, and ceiling.
Overpressure is the reason that wearing hearing protection cannot prevent the health effects that officers experience when training on a range without noise mitigation. It’s one of the primary causes of the nausea, fatigue, and other effects some officers experience after a long training session.
Absorbing the Noise
Troy Acoustics’ strategy for mitigating range noise is to absorb the noise and the overpressure energy without reflection. It accomplishes this goal by placing proprietary material at key positions on the range. Bergiadis says the results are not dependent upon the range’s design.
The company’s proprietary material consists of two elements: Troy Board and Troy Wool. The Board is composed of ground up pine fibers, Portland cement, and water. The material is combined in a mold and formed under high pressure. Troy Wool is applied behind the Troy Board. The Wool is composed of fibers spun from melted basalt rock that is impervious to the elements and mold, unlike fiberglass. Both the Troy Board and the Troy Wool have been independently tested and certified as “zero flame spread and zero smoke development. It will not sustain and will not support combustion,” Bergiadis says.
The ballistic performance of Troy Board has also been tested by the U.S. Air Force for ricochet and splatter. “If an errant round hits a baffle treated with the Troy materials, it will not ricochet toward the shooter and fragments will not splatter through the range,” Bergiadis says. He adds that the Air Force shot the Board from one meter away with 9mm, .40, 5.56mm, and 7.62mm while he watched. “And it held up tremendously well.”
The Clearwater (FL) Police Department is now a prime example of an agency that experienced residential sprawl around its training range and complaints about noise from its new neighbors.
In Clearwater, the neighbors alerted the media. And the range noise they experienced ended up on the local TV news, complete with video of gunfire across the street from a high school.
The range itself was relatively new, five years old, and it had been shut down for a year while a new noise mitigation system was installed. That was before the complaints that were shown on the local news. In an attempt to reduce the complaints, Clearwater PD had to redo the noise mitigation and hired Troy Acoustics to do the job.
Bergiadis says that after the installation of the Troy system, the neighborhood experienced less noise from the range. “The gunfire is no longer intrusive,” he explains. “You want to get to the point that the gunfire noise is in the background not the foreground and it blends in with other noise in the neighborhood like traffic sounds.”