I was working in a lab one day by myself and kept hearing a faint voice somewhere in the room; this turned out to be an AM station that was being picked up by t

I was working in a lab one day by myself and kept hearing a faint voice somewhere in the room; this turned out to be an AM station that was being picked up by the drive coils of an old seismograph-type pen plotter and vibrating the mechanism enough to produce sound.