THERE’S bad news if you like to crank up the volume while listening to your iPod.

　　A new study by a University of Colorado at Boulder researcher and a Boston audiologist reveals that consistently listening to an iPod or similar MP3 player at the highest volume levels - even if just for a few minutes a day - can cause long-term hearing damage.

　　It would take only 5 minutes a day of listening to an iPod full-blast to cause hearing damage, according to the study, conducted by Colorado doctoral student Cory Portnuff and Brian Fligor, a doctor at Children’s Hospital Boston.

　　While the concern about too-loud music players has existed for years - going back to the days of the Sony Walkman - Portnuff and Fligor’s study is the first to quantify how much is too much.

　　Portnuff said the popularity of iPods and other MP3 players drew his attention.

　　“I did notice that students, in my opinion, are carrying portable electronics more often now,” he said. “And as there was no research in this field, I decided to undertake this.”

　　The study used a microphone to record volume outputs from six kinds of MP3 players and five kinds of earphones. Using a computer, the researchers then compared those outputs to already existing safety standards on noise levels that cause hearing loss when using industrial equipment.

　　All the MP3 players, regardless of whether they blasted heavy metal or smooth R&B, were capable of producing 100 decibels or more at full volume. That’s the equivalent of having a running chainsaw next to you or being at a loud rock concert, Portnuff said.

　　The study found that for all earphone types, listening at 50 percent volume or less posed no risk, and listening at 60 percent volume posed a risk only if done 14 or more hours a day with certain styles of earphones.

　　But, beginning at 70 percent volume, the study noted a steep decrease in the amount of time a user could safely listen to music. At full volume and for all earphones, listeners have only a few minutes a day before facing damage.

　　Portnuff said “it literally takes 10 years before this shows up. So the fact I see it at all is concerning.”

　　“People are putting themselves at risk by listening to these devices at high levels,” he said.