Going back over a hundred years ago, one of the fathers of modern electricity and several studies on magnetism was experimenting with something like a crystal radio circuit which gets sounds out of electromagnetic sources.
The sounds were spooky, and Tesla thought it had some sort of supernatural source.

And now you can do it yourself to get your own conclusions out of it!
Try it out at the Instructables Spooky Tesla Spirit Radio page!

Source: Gizmodo