Here's medical advice worth listening to -- before it's harder to listen to anything: Don't blast music through ear buds or headphones. New research shows that one in five U.S. teens has at least slight hearing loss -- a 30-percent jump from just 15 years ago. Repeated, hours-long exposure to iPods and other MP3 music players may be a major reason, indicates the study published last month in the Journal of the American Medical Association.
Listening while exercising, in cars and in planes can be particularly risky if the volume is raised so music can be heard over external noise.

MP3 players -- which don't always show volume levels -- reach 100 decibels or more. The recommended safe sound level is 70 decibels on average throughout each day. Noise suppression earphones for use with MP3 players can reduce external sounds, letting users enjoy music at lower levels. Ringing in the ears or fuzzy-sounding speech after using a digital player are warning signs to get a hearing test. Hearing loss could cause problems in school and set the stage for hearing aids in later life.

A New York researcher believes iPods are just part of the problem for teens with part-time jobs in loud workplaces or "other opportunities to be exposed to excessive sources of noise, including noisy bars and restaurants, sports events, concerts, motorcycles." The specialist, Professor Robyn Gershon of Columbia University, adds: "All these exposures, when combined, could readily exceed the recommended limits."

Teen says: "My hearing sounded strange. It sounded muffled, it didn't sound like what I would normally hear." -- Lindsey Claus, diagnosed with hearing loss from playing French horn in an orchestra

Safety tips: Set a safe listening level by turning a player to full volume, then back to halfway. Also, take "listening breaks" from loud music or other noise sources to let ears recover.

Other advice: "If you turn it all the way up, you can listen safely for only five minutes. If you listen at a lower level, you can listen for longer periods. You can listen at 60 percent or lower all day without increasing your risk for hearing loss." -- Cory Portnuff, doctoral student in hearing science at the University of Colorado at Boulder