Music headphones can interfere with heart devices

"Have a pacemaker or an implanted defibrillator? Don't keep your iPod earbuds in your shirt pocket or draped around your neck - even when they're disconnected. A study finds that some headphones can interfere with heart devices if held very close to them. They might even prevent a defibrillator from delivering a lifesaving shock, say doctors who tested them. 'Headphones contain magnets, and some of these magnets are powerful,' said the study's leader, Dr. William Maisel, a cardiologist at Beth Israel Deaconess Medical Center in Boston and a heart device consultant to the federal Food and Drug Administration" - AP