"The students were always asking me to turn up the volume, and the faculty were always asking me to turn it down," Burnett said. "That got me to thinking that there might be a problem."
The study found that at 50 percent of maximum volume, the fitness-renter sound system was safe. At 75 percent, it posed a risk.
Burnett said young people are better able than older adults to tolerate high-decibel music, and as a result are unaware of the damage they could be doing.
The fitness-center study did not account for the use of portable MP3 players, which some doctors say are leading younger and younger people to show signs of hearing loss.
The Wall Street Journal reported in January that hearing specialists say the effect they're seeing now may be only the beginning, because accumulated noise damage can take years before it causes noticeable problems. Researchers at Children's Hospital Boston recommend that the exposure limit for safe headphone listening is one hour a day with the volume no greater than 60 percent of the maximum.
In fitness centers, group-exercise classes are a particular concern because of participants' long exposure to very loud music.
Since the study, Burnett said, he's kept the music volume at 50 percent at the Fort Hays fitness center, sometimes drawing complaints from students.
"When it's possible, I try to explain to them that we did a study and that we're keeping the loudness at a safe level," he said. "Usually, they're pretty understanding."
