Could rocking out to your favorite tunes with a portable music player put your heart at risk?

That's true, but only if you have a pacemaker. The NY Post reports that magnets in headphone speakers can interfere with the medical device if they're draped near your chest.

"Headphones contain magnets, and some are powerful," Dr. William Maisel said yesterday at an American Heart Association conference. "It's smart to keep small electronics at least a few inches from implanted medical devices."

Rock on.