Watching What You Say JUNE 1, 2016 We don’t really think about sound all that much, and when we do, we rarely think of it as something physically traveling through space. But that’s really how sound works. Sound waves are pressure waves — they cause vibrations in the area around them. When we hear those sounds, it’s because those vibrations strike our eardrums, some more stuff happens , and ultimately, our brains translate that into meaningful (or meaningless) noise. But when we’re having conversations, those pressure waves don’t just go into our ear. They bounce around the room, hitting against everything from the bag of potato chips on the table to the windows and doors. So it logically follows that, if your conversations are causing glass windows to vibrate, maybe those vibrations can be seen from the outside — by people who would not otherwise be able to hear you conversations. Actually, there’s no “maybe” about it. In May of 2011, the United States raided a compoun
