Research Team Studying Noise Exposure in Firefighters for Better Treatment of Hearing Loss

By: Joslyn Cassano | Published: June 2, 2023

The noise all around us – at work, at home, at concerts and sports events, when we travel – can have a lasting impact on how well we hear. University of Miami researchers Suhrud Rajguru, Ph.D., and Hillary Snapp, Au.D, Ph.D., are interested in better diagnosing and treating noise-related damage to the ears for everyone.

“We consider this a global health challenge because noise is everywhere,” says Dr. Snapp, who is chief of the Miller School of Medicine’s Audiology Division. “We are exposed to some level of noise every day, but most of us are not good at determining when noise is dangerous for us, and we don’t have the tools or resources to protect ourselves in real time.”

When Dr. Snapp and Dr. Rajguru first began to explore their interest in noise-induced hearing loss and prevention, they realized the challenges of understanding noise exposures in the broader general population. To better grasp how noise impacts all of us, they set out to first fully understand the impact of noise in one occupational group, firefighters.

Over the past two years, with grant support from Miami Clinical and Translational Science Institute (CTSI) and the University of Miami’s Laboratory for Integrative Knowledge (U-LINK), Dr. Rajguru, Dr. Snapp along with Barbara Millet Ph.D., Natasha Schaefer Solle, Ph.D., R.N., and their multidisciplinary team have created a body of research that continues to grow, and shows promise for better diagnosis, prevention, and treatment of noise-induced hearing loss. They are also identifying early and important changes in balance function in this occupational noise-exposed group.

“We are fortunate that the University of Miami, Miami CTSI and U-LINK, part of the effort by the Office of Vice Provost for Research, support and facilitate translational research,” says Dr. Rajguru, professor of Biomedical Engineering and Otolaryngology at the University of Miami and a founder and Chief Scientific Officer of RestorEar Devices.

“In addition to providing the initial seed funding for this work, Miami CTSI provides an immense amount of support from recruitment resources to writing resources to working with the IRB,” says Dr. Snapp, who is also a Miami CTSI Eureka scholar. “CTSI champions the work of clinician scientists. Without them, this project wouldn’t exist.”

The CTSI provides grant writing workshops, research mentoring training, education for business model development and commercialization of research among other resources to the broader University community, says Dr. Rajguru, who also co-directs the CTSI’s Translational Workforce Development and Collaboration and Multidisciplinary Team Science programs.

Part of the U-LINK mission is to encourage team science, or collaboration between disciplines that might not ordinarily communicate or combine efforts. The UM team studying noise exposure in firefighters brings together researchers and professionals from the fields of otology, neurotology, audiology, engineering, physical therapy, nursing, public health, and communication.

“With issues affecting population health, there’s so much that needs to be considered beyond what I can do as an audiologist and what Dr. Rajguru can do as an engineer,” says Dr. Snapp. “U-LINK has pushed us to think more about how we can incorporate the expertise of our colleagues.”

In partnership with the Sylvester Comprehensive Cancer Center’s Firefighter Cancer Initiative and its co-deputy director and research assistant professor Dr. Natasha Schaefer Solle, the hazardous noise research team used the built-in “Health” app on Apple Watches to study the types of noises firefighters are exposed to at work.

“What we observed is that during a 24-hour service, firefighters get significantly more noise exposure from alarms, radios, and other communication equipment, the engines and water hoses compared to the non-firefighters. And the noise persists for a longer time,” says Dr. Rajguru.

Loud music at a concert or the elevated sound levels of a busy restaurant can impact any person’s hearing, but the cumulative exposure to hazardous levels may be much less when compared to a firefighter’s shift at work.

Firefighters are repeatedly exposed to brief but intense noise throughout their shifts. Because the Apple Watch does not always successfully capture very brief, loud sounds like a gunshot or explosion, chances are that the exposure is even higher in firefighters than the data show, says Dr. Snapp.

A follow-up study used firefighter focus groups to examine knowledge and attitudes toward noise exposure. Most firefighters begin their careers in their late teens and early twenties, making them eligible for retirement in their 40’s, according to Dr. Snapp.
An individual may not show any signs of hearing loss until much later in life, which can make prevention a challenge. “The damage is done, but it may not be measurable until they are older because of delayed onset,” she says.

The focus groups and one on one discussions with firefighters revealed that a firefighter’s primary concern is doing their job to their best ability, in often complex and dangerous environments. An intervention, such as ear plugs, may interfere with their ability to hear important information.

“A firefighter told us that they would rather be deaf than dead,” says Dr. Rajguru. “Given their nature of work, this is completely understandable. But we really needed to go into the fire stations and hear it from them, to appreciate their environments and the limitations. We learned that the current devices for hearing protection are inadequate, and we need better approaches to help our firefighters and other active duty service members.”

Christopher Bator, division chief for safety and health at the Coral Springs-Parkland Fire Department, says the hearing protection currently available to most firefighters is not designed for the realities of the job, which requires heightened awareness of surrounding sounds and situational awareness. At the same time, he’s observed a greater need for protection, as firefighters appear to be suffering hearing loss at younger ages.

“There is such value in the research coming from UM to identify the problem of hearing loss in firefighters,” says Chief Bator, who also serves as the President of the Florida Firefighters Safety and Health Collaborative. “As a result, individuals can take the necessary precautions, organizations can make investments in hearing safety, and hopefully it will lead to the development of new technology that meets the demands of the job while making sure firefighters are protected.”

Dr. Barbara Millet, professor in the University of Miami School of Communication, helped the research team look at “human factors,” or the things that make a person likely to undertake an intervention, adopt a behavioral change, or new technology. “This is such a critical aspect,” says Dr. Snapp. “If it’s not acceptable to the end user, you’re never going to be able to implement it.”

Although interventions have been difficult to implement, Dr. Rajguru says there is an interest in prevention, especially from firefighters who are experiencing hearing loss. “They would love solutions, not only for themselves, but for those new to the fire service.”

Bolstered by new data and insight, the research team has begun to explore other aspects of hazardous noise exposure for firefighters, including better diagnostics. Currently, the most widely used hearing tests do not assess or evaluate all the features of hearing, says Dr. Rajguru. Further research will lead to the development of more sensitive clinical tests that would detect early and small changes in hearing.

“We now have data from more than 400 firefighters looking at early changes in their hearing and balance function,” says Dr. Rajguru. “Typically, within the first year of service we start to see these changes, but only if we use more sensitive tests. There are changes we cannot detect with standard clinical tests.”

Dr. Rajguru hopes the team’s work will also lead to the development of new therapeutics. His research group is studying the benefits of cooling the ears to reduce inflammation and damage to sensitive structures after noise exposures have happened for firefighters, and eventually, for everyone. “That includes military groups, construction workers, as well as ordinary citizens who are getting exposed to noise all of the time,” he says. “We want to ensure that we can take what we have found and move it out to benefit patients everywhere.”