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When the tabloids want to record a compromising conversation they normally
bug a room or wire up a journalist with a concealed microphone. Now, the
Japanese company Kyoyu of Tokyo is patenting a system that lets you eavesdrop
without planting a bug (WO 99/6804). The system exploits the fact that a
conversation will cause the window panes to vibrate slightly. The eavesdropper
beams a laser onto a window and a receiver picks up the reflected beam. The
vibrations of the window caused by speech are then amplified and recorded.