40 () posted 3 years ago by ghost_of_aswartz 3 years ago by ghost_of_aswartz +40 / -0 10 comments share 10 comments share save hide report block hide replies
Similar to the old Israeli trick to visually measure the vibrations of a hanging lightbulb to capture the sounds in a room.
Soviets did that using windows of rooms where meetings were taking place. Im sure there's more than a few cold war methods of doing this.