A new report refutes claims that portable music players, such as Apple’s iPod, interfere with cardiac pacemakers.Howard Bassen, a researcher with the U.S. Food and Drug Administration in Rockville, Md., led a research team that measured the magnetic fields produced by four different iPod models: a fourth-generation iPod and an iPod with video, and an iPod nano and iPod shuffle. They also measured the voltages delivered inside the pacemaker by the magnetic fields from the iPods. All …