Using an Ordinary Light Bulb To Spy On Conversations 80 Feet Away

Security researchers at the Ben-Gurion University of the Negev and the Weizmann Institute of Science in Israel, have been looking at methods of eavesdropping on private conversations. They can eavesdrop on conversations from as far as 80 feet away thanks to a hanging light bulb. Fluctuations in air pressure on the surface of the hanging bulb are created by the sound of conversation, or music, and make a hanging bulb vibrate.

It is not as easy as you may think. The hackers need a clean line of sight between their electro-optical sensor-equipped telescope and the hanging light bulb concerned. So, if the curtains or blinds are closed on a window, or the light bulb sits behind a lampshade of some sort, then this eavesdropping method will fail.