Marine Corps Base Quantico -- There has been an uptick in reported hearing injuries aboard Marine Corps Base Quantico.
“We have all the big guns here,” said Edwin Ventura, safety manager at The Basic School. “And we have instructors who are here for three, four, even five years and are continually exposed to the sound of these weapons during that time.”
The new Hearing Conservation Task Force, made up of audiologists and industrial hygienists from Naval Health Clinic Quantico (NHCQ), TBS Range Management Branch and other interested parties, is dedicated to ensuring that current and future Marines are shielded from the effects of high-decibel noise. At a Jan. 12 meeting, the task force viewed a demonstration of the LxT sound level meter, a device that can collect and store groups of decibel-level measurements for comparison.
“We’re looking to measure impulse noise from weapons firing,” said Corey Bender, NHCQ industrial hygienist. “The recommendation is for single or double hearing protection under a 165 decibel peak. We need a reliable way to see whether a rifle is above that level.”
The Occupational Safety and Health Administration’s (OSHA) permissible exposure limit is 90 decibels for all workers for an eight-hour day. When the noise level is increased by 5 decibels, the exposure time is cut in half. The sound of a power mower equates to about 95 decibels. Permanent hearing loss can be caused by noise of that decibel-level when exposure is regular and sustained.
Noise at 150 decibels can penetrate bone and just one exposure to noise at 170 decibels can cause permanent damage. Almost all firearms create noise that is over 140 decibels.
According to the OSHA website, some of the effects of hearing loss include tinnitus (the sensation of hearing buzzing or ringing in the ear), isolation, difficulty concentrating, stress, ulcers and hypertension.
Bernard Truesdale, a sales representative for Larson Davis, a division of PCB Piezotronics, presented the LxT meter to the task force.
“This is a very straightforward device,” he said. “It’s designed to capture peak measurements and is able to group measurements of separate gunshots.”
The LxT can take noise-level measurements 15,000 times a second and has two GB of internal memory. According to Truesdale, current users of the device have found it only needs to be calibrated every 24 months. The meter with its software will cost $4,000.
Jolene Mancini, audiologist with NHCQ, tested the device by clapping into it. Her hand claps measured 108 decibels.
One problem the task force found with the LxT is that it has an overload point of 165 decibels, meaning that it will not record measurements over that level. Many artillery pieces used in training aboard Quantico would exceed that level.
Larson Davis is working on production of a one-inch pre-polarized microphone that would fit on the LxT and would allow it to capture lower frequencies and noises up to a higher decibel level. Bender said he thought this new microphone would be better for the task force’s purposes. The new microphone is not yet available for purchase, but is estimated to be in the next few months. It will be priced at $900.
Bender said the task force will consider the device and look at others. He also said the group is looking to invite researchers from the National Institute for Occupational Safety and Health to take sound level measurements at the range using their own equipment.
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