A new scientific study brings bad news for iPod lovers. 

The report found that those who listened for five hours a week at high-volume settings exposed themselves to more noise than permitted in the noisiest factory or work place. The study also warns that people may not realize the damage until years later.

“Regularly listening to personal music players at high-volume settings when young,” the report said, “often has no immediate effect on hearing but is likely to result in hearing loss later in life.”

Users listening at high volumes for more than an hour a day each week risk permanent hearing loss after five years. This is equivalent to 5 percent to 10 percent of the listeners, the study concluded.

“Some authors stress that if young people continue to listen to music for long periods of time and at high volume levels during several years, they run the risk of developing hearing loss by the time they reach their mid-twenties,” the report said. “Among young people, there are many reports of temporary or persistent tinnitus induced by loud music, but very few studies have focused on the relationship between the use of personal music players and tinnitus.”