About 40 million adults in the United States ages 20 to 69 have noise-induced hearing loss. This is caused by exposure to loud sounds, either from a sudden loud noise like a firework or repeated exposure to loud sounds over time, like a lawn mower.

Wearing hearing protection can help prevent noise-induced hearing loss, but for people in certain professions, hearing protection often makes work more challenging. That’s why an interdisciplinary team of researchers at the University of Minnesota Duluth (UMD) are working to find better earplugs for two populations: musicians and referees.

“We're looking to find the earplug that will work for a specific scenario the best,” said David Anderson, PhD, an assistant professor in the Department of Electrical Engineering. For musicians, that means reducing the level of sounds without distorting the instrument’s musical characteristics; for referees, that means blocking out the impulsive parts of the whistle sound, but retaining speech sounds.

Anderson is collaborating with Brent Fisher, an audiologist and assistant professor from the Department of Communication Sciences and Disorders, and Ryan Loken, PhD, an instructor from the Department of Music, to look at the study from a variety of angles. The team records percussion and whistle sounds using a special device that resembles a human head, with microphones built into the ears. Anderson then processes the data to determine how instruments and whistles sound when using different types of earplugs. It’s similar to work he’s done for a defense contractor to help members of the US military maintain spatial awareness while in combat, and he’s excited to put it to use for other populations.

“It's been really cool to be an engineer and work on something that lets me go into music halls and meet with people outside of engineering,” Anderson said.

Once data collection and processing is complete, the team will share their findings with industry partners who manufacture hearing devices, and with the Minnesota State High School League to give guidance on the use of hearing protection for referees.

“My hope is that this work is something that translates into a behavioral change in the community,” Fisher said.

And that might just help lower the number of people who experience hearing loss in the future.

Hitting the right note

When Ryan Loken first learned to play drums, his dad made him wear a pair of large hunting earmuffs.

“Hitting a symbol back then was just full force, full volume all the time,” he said. “Being told that I needed to have my ears protected really started me down this journey.”

That journey led Loken to UMD, where he works as an assistant professor of percussion. He incorporates mobility, calisthenics and sports medicine principles into his teaching in an effort to promote healthy, lifelong musicianship. So when Loken was approached by his UMD colleagues to partner on earplug research, the conversation hit the right note.

“Percussion is my life,” he said. “But how can I take care of my hearing so that my profession won't suffer?”

Loken has been recording a variety of percussion instruments in Anderson’s lab. It’s a simple process, he said, but having to repeat the same note several times with consistency has helped him hone his technique. And collaborating with faculty in other disciplines has broadened his understanding of hearing and sound.

“We're hoping that through our research, we can get different earplugs and know what they can actually effectively protect against,” he said. The work has also given Loken more data to share with his students to encourage them to protect their own ears.

“Telling students that they need to wear earplugs is one thing. Showing them the actual empirical data—that can really help,” he said.

Making the right call

Jeremy Uecker began officiating soccer in Duluth when he was 13 years old. That was 30 years ago. Since then, he’s blown his whistle an estimated 80,000 times. In 2020, he also began officiating basketball and noticed the sound of his whistle was much more noticeable indoors compared to outside on an open field.

“Because of that environment, it did have more of an impact on my perception of how loud and oppressive the sound was,” he said.

Around that time, Uecker took an online hearing test and learned that he couldn’t hear many high frequencies. For the first time, he began thinking about the impact blowing his whistle has had on his hearing. So when he learned that a group of researchers at UMD were looking to speak with people like him, he “jumped at the opportunity.”

“The human voice has a different frequency than my high-pitched whistle, and so if there were a way to protect against the higher pitch but still allow the voices to come through,” he said, “that's what I would see as the ideal solution.”

Uecker visited Anderson’s lab and blew his whistles in an enclosed soundbooth to help the research team gather data. He also shared his experience as a referee. In all his years officiating, he said he’s never seen a fellow referee wear hearing protection. Part of the reason for that, he said, is that referees need to be able to hear what’s going on around them, and at times, have quiet conversations with coaches or players. If better earplugs for referees were available, Uecker said adopting hearing protection would be an easy call to make.

“The impact of the university to further scientific knowledge,” Uecker said, “is a great thing for the community and something that I think we can really take pride in.”

Header image caption: The research team uses a special device that resembles a human head, with microphones built into the ears, to record percussion and whistle sounds.