There have been a series of articles published in the last few months. I am posting links below so that you can learn more:
- Rolling Stones magazine article feature a report with Pete Townshend here
- EarBud.org is a web site sponsored by the House Ear Institute. There are hosting the MTV commercial on the risk of listening to music at loud levels. Also very informative site with some general guidelines on MP3 player use. Click here to visit their site.
There is direct relationship between the loudness level and and how long you should use the devices. Volume levels which are at 60% of the available level, really should be use for more than 1/2 hour per/day. If you listen at lower levels, you can significantly increase your usage per day.