@woody@pleroma.pch.net "Laser" is one way to say it -- no light involved We are looking here at phased arrays of small speakers, all sending the same sound wave, each applying a delay so that the sound waves superpose and add at one exact point in space. I remember a demo of that tech at a Microsoft Research fair years ago. The effect is weird. The target hears the sound, nearby people just hear low level noise. By the way, the same principle also works for sound capture.