Audiologists Brian Fligor and Terri Ives and audiology doctoral candidate Cory Portnuff conducted an extensive study on the connection between listening devices and hearing loss. In papers presented in 2006, their research suggested that listening to music in a quiet environment using "in-the-ear" earphones designed to block out background noise provided listeners with the least chance of hearing loss.
The research team used five portable players and four types of earphones in their studies. Findings showed that the types of players made no difference in sound levels but that the types of earphones did. The team also found that there was no difference in the highest audio levels across five music genres. In other words, loud music is loud music.
Bottom line: use parental common sense. Talk to your kids about both their choice of music and the volume at which they listen to it. Music itself can't hurt your kids, but extremely loud music can. For more information about this study and for links to the papers themselves, follow the link below to the original article on Physorg.com.

