Earbuds areplaced directly in the ear and can boost the sound signal by as much as six to nine decibels. It’s enough to cause hearing loss after only about an hour and 15 minutes.
The recommendation si what the reasearchers call the 60 percent/60 minute rule. they recommend using the MP3 devices, including iPods, no more than about an hour a day and at levels below 60 percent of maximum volume.
To avoid permanent hearing loss in the middle ranges --the range required to hear conversation in a noisy restaurant, for example -- they recommends the older style, larger headphones that rest over the ear opening.
Another option is the use of noise-canceling headphones that eliminate background noise so listeners don't have to crank the volume so high.
Source: http://www.northwestern.edu/newscenter/stories/2005/12/garstecki.html
Review: December, 2005
