A cellphone ringing, a siren approaching, a gunshot sounding in the distance. We depend on our hearing in many dynamic situations to make informed decisions about our surroundings. People working in the armed forces, construction, and public safety, however, depend on their sense of hearing to stay alive. 

According to the Centers for Disease Control and Prevention, veterans are 30 percent more likely to have severe hearing loss than the general population.

“Hearing loss and tinnitus represent the largest injuries in terms of money spent for the U.S. military, in terms of money spent. For over 3 million affected service members, over a billion dollars per year are spent on medicines, tinnitus therapy, hearing aids, surgery or other medical care,” said College of Engineering researcher and John Grado Endowed Professor John Casali.

The challenge is this: Soldiers, first responders, and construction and industrial workers need to hear sounds from all directions to detect threats, hear warning signals, and communicate with co-workers. At the same time, the delicate neural structure of the inner ear needs to be protected from loud sounds such as gunfire. Hearing is always "on" and omnidirectional, unlike vision, which requires focus. When hearing is injured or impaired, its value to human functioning becomes evident.

“When your life depends on your hearing, and your hearing depends on your hearing protection, auditory situational awareness presents a conundrum.” Casali said. “When people lose their auditory situational awareness, they are often compromised in their work and as a result may not be able to continue in certain mission operation specialties.”

Casali and researchers in the Grado Department of Industrial and Systems Engineering (ISE)  have made significant strides in improving hearing protection and situational awareness for military personnel through the development of a groundbreaking training system. The Portable Auditory Localization Awareness Training (PALAT) system thoroughly tests military-grade hearing protectors to see how they impact a soldier's ability to detect, recognize and localize sound, as compared to the open, natural ear.

A compact, portable training tool, the PALAT system can be set up in an office environment, barracks, or other military-training locales. The fold-up style and size were designed so subjects could easily and efficiently perform the headset training. It also provides trainees with an immediate, objective score for their performance, compares them with other trainees, and adapts to their performance to provide additional training as needed. Involving a diverse team of researchers over the course of 11 years, the final PALAT prototype was developed entirely at Virginia Tech.

John Casali
John Casali. Photo by Jordi Shelton for Virginia Tech.

Researchers

Key Players

  • HEAR, LLC (Hearing Ergonomics & Acoustic Resources, formed by Casali)
  • The Hearing Center for Excellence, Department of Defense
  • Radford Ammunition Plant
  • Virginia Tech Corps of Cadets as test subjects for the devices
  • ISE Instrument Makers
  • Harris Manufacturing Lab
John Casali, Brandon Thompson, and Kichol Lee
From left: John Casali, Brandon Thompson, and Kichol Lee with the PALAT system installed at the United States Military Academy at West Point. Photo courtesy of John Casali.

Farm-to-lab research

In 2013, the Department of Defense’s Hearing Center for Excellence approached Casali and Kichol Lee when they realized there was no way to objectively assess how well a soldier could detect sound and determine its source and direction. From this sponsored research project, the Detection, Recognition-Identification, Localization and Communication test system - a precursor to PALAT - was created.

In the early phases of their research, tests were conducted at Casali’s farm in Pulaski County and the Radford Army Ammunition Plant. Subjects wore hearing protection while non-lethal ammunition was fired around them, then attempted to detect the sound of the blank and localize it. This unique in-field setup allowed researchers to measure both the response time and accuracy in detecting and localizing the sound.

Casali said, “With an open ear, the response time was around two seconds for gunshot detection and localization. However, when using one of these military-grade headsets, an electronic earmuff, the response time increased by 0.9 seconds, which is a significant disadvantage in a combat situation."

The next challenge, however, was the portability of the testing. Researchers recognized the need for a dual-mode testing and training system that could help soldiers develop their ability to maintain situational awareness while using hearing protection before they were deployed.

"The idea of PALAT was to create a smaller, portable version that could be deployed to different military bases,” Lee said.  “Soldiers could then use the system during downtime to train with new devices and learn how to use them for optimal performance."

Kichol Lee
Kichol Lee stands at the door of the Reverberant Chamber in Auditory Systems Laboratory where researchers test hearing devices. Photo by Jordi Shelton for Virginia Tech.

PALAT makes perfect

The PALAT system not only tests military grade headsets - it efficiently trains users to detect, recognize, and localize sounds, which is critical for maintaining situational awareness while in combat.

“The system needed to fit into an average office space, be collapsible for transport, and rugged enough for military use while providing all the same acoustical cues,” said Thompson, who currently serves as academy professor and systems design and analysis center director at the United States Military Academy at West Point. “I used an iterative design process, similar to agile project management, to create a system that expands and collapses like an umbrella.”

Thompson worked closely with the Harris Manufacturing Lab to refine the design. The final prototype was developed entirely at Virginia Tech with support from ISE instrument makers Mark Montgomery, Kelly Snidow, and Randy Waldron.

Lieutenant Colonel Kara Cave, who currently serves as the Army Surgeon General's consultant, and hearing program manager for Fort Liberty in North Carolina, worked to evaluate the effectiveness of training for the PALAT system.

“The great thing about the system is that it’s a rapid means to evaluate a hearing protector or the effects of something other than the open air,” Cave explained.

Eventually, the hope for PALAT is that it can help military service members as well as first responders everywhere protect their hearing without compromising their safety.

As of 2024, the PALAT system has been under beta-testing at several military installations including West Point and the “Gruntworks” facility for the Marines Expeditionary Rifle Squad at Quantico, Va., where it has received positive feedback. Additionally,

  • The Virginia Tech team was recognized with the international “Safe-in-Sound Award” from the National Institute of Occupational Safety and Health
  • Casali delivered a keynote speech at the international Hearing Across the Lifespan, or HeAL, conference in Como, Italy in June, 2024

Casali said, “Our lab-to-field experiments validated that training with the PALAT system significantly improves auditory situation awareness, and this improvement transfers to real-world environments. If a warfighter or worker gains more confidence that they are indeed situationally aware while wearing their hearing protector, then they are much more likely to use it, and the result will be a reduction in the tragic incidence of noise-induced hearing loss.”

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