Silently ‘speak’ to someone across the room with an ultrasonic beam
 

If you ever wanted to whisper across a crowded room, a new experimental device might let you deliver sneaky instructions -- if the awkward speaker and electrodes don't tip everyone off. Researchers at the University of Bristol built a wearable that t...

https://www.engadget.com/2017/05/15/...trasonic-beam/