The next time students are jamming to 50 Cent on their MP3 players, they might want to refrain from blasting the song at full volume.

Listening to music with headphones for over 90 minutes a day at 80-percent volume can lead to long-term hearing loss, according to a Harvard Medical School (HMS) study presented at a conference yesterday.

“This is your speed limit for your MP3 player,” said Cory Portnuff, a co-author of the study who is a doctoral candidate at the University of Colorado. “Every time you increase that level, you increase your risk of developing hearing loss even more.”

Hearing loss is gradual, and it may take up to 10 years to finally set in, according to researchers. But this means teenagers and college students blasting music now may be at risk of developing hearing loss at a relatively young age, Portnuff said.

“The 16, 17 year olds now who are using their headphones inappropriately may have pretty whopping hearing losses and will have to spend the rest of their lives dealing with the fact that they cannot hear at proper levels,” said the study’s main author Brian J. Fligor, an audiologist at the Children’s Hospital Boston and an instructor in otology and laryngology at HMS.

The study looked at five different MP3 players and measured their absolute volumes with a microphone. Using existing criteria to determine the risk of hearing loss, researchers assessed how much damage each music player caused when played at increased volumes.

Portnuff said that he found no differences in volume levels between hip hop, rock, or rhythm and blues.

“We found absolutely no difference between different genres of music,” he said. “They all had the same output levels.”

A separate study Fligor co-authored with Terri Ives, a professor at Pennsylvania College of Optometry, found that only six percent of the population listens to music at excessive volume levels when there is no background noise. But with background noise, this number increased dramatically to 80 percent.

The findings from these studies have prompted some students to turn down the volume.

“I used to listen to my iPod a little louder,” said Kristina Ranalli ’10, who said she had heard of Fligor’s study. “But now I’m listening to it no more than halfway up.”