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Battlespace acoustics branch protects hearing, human performance

  • Published
  • By Shireen Bedi
  • Air Force Surgeon General Public Affairs

Hearing loss is a significant disability and can seriously impede an Airman’s mission capabilities. Using appropriate hearing protection devices, or HPDs, can prevent this damage.

Researchers from the Warfighter Interface Division, Battlespace Acoustics Branch, part of the 711th Human Performance Wing at Wright-Patterson Air Force Base, Ohio, focus on protecting Airmen’s hearing by studying existing devices used during various tasks and noise environments, and develop new ways to measure the impact of HPDs on mission performance.

“Studying how well HPDs work is key to reducing the risk of hearing loss,” said Hilary Gallagher, a biomedical engineer and Acoustics Branch deputy branch chief. “Hearing loss is still one of the top disabilities among veterans.”

The Acoustics Branch, in operation for nearly 70 years, focuses on all aspects of acoustics and communication, and its effect on human performance.

“Human performance is central in everything we do,” said Dr. Eric Thompson, a research engineer with the Acoustics Branch. “This includes looking at the effects of noise on the human, what sounds are audible or harmful, and how well Airmen can complete their mission in adverse noise environments. Those are the kinds of issues that we are fighting against and trying to improve.”

Acoustics Branch researchers start by collecting data from operational environments, analyzing the level and qualities of noise to better identify what HPDs would work in a particular environment.

“We look at how noise is being generated, how it propagates, and what that means for Airmen in the field,” said Gallagher. “Until you know what kind of noise you are up against, it’s hard to select what HPDs work best.”

To understand this, the Acoustics Branch researchers go out into operational environments to measure specific noise exposure.

“In 2013 we went out to Edwards Air Force Base to measure the F-35 aircraft to learn how the aircraft sounds in the air,” said Gallagher. “From that, we got a better understanding of the noise that aircraft maintainers and the community may be exposed to.”

With this specific noise exposure data, the Acoustics Branch researchers can bring those noise recordings and measurements back to their facilities that is equipped with advanced capabilities to study HPDs in a simulated noise environment.

One such capability is the Acoustic Branch’s Auditory Localization Facility, or ALF, which allows researchers to understand sound localization in a simulated environment.

“ALF is a large chamber with 277 loudspeakers distributed in a fixed, spherical array,” said Thompson. “We have the ability to turn on any one of those speakers independently to do refined sound localization experiments, to understand the impact of an HPD on the wearer’s ability to detect and localize sounds in their environment.”

Currently, the Acoustics Branch is conducting a series of experiments looking at the relationship between sound localization and the time it takes to acquire a visual target.

“These experiments look at HPD’s direct impact on human performance, providing those in the field data illustrating how sound localization impacts mission capabilities,” said Thompson. “When we tell them that it may take you three seconds longer to find a target when wearing a certain HPD, then that provides a more mission-relevant performance metric.”

The Acoustics Branch also develops updated methods and standards to assess new devices.

“Currently there is no standard for measuring sound localization while wearing HPDs,” said Gallagher. “This presents a challenge for the acquisitions community when writing specifications and requirements for acquiring a new HPD without standards to lean back on.”

Acoustics Branch researchers are working to draft these standards and get the right devices into the hands of Airmen who need them.

“HPDs are just like shoes you put on your feet,” said Gallagher. “What one Airman prefers can be completely different from another Airman, or what one mission requires may be completely different from another mission. That makes it difficult when selecting appropriate HPD.”

Despite those challenges, Acoustics Branch researchers remain focused on improving Airmen capability and protecting human performance.

“Classic foam earplugs are great for some missions and environments,” said Thompson, “But there are a lot of new devices we can now offer Airmen in various operational environments that provide appropriate protection and allow the wearer to hear mission-critical signals.”