Ultrasonic Directional Speaker

Last modified by Victor Zhang on 00:19, 22/07/2020

Open source one:https://hackaday.io/project/9085/logs
Probably first saw in "future weapons" as a military equipment for crowd control
It uses the directional properties of ultrasound
- Modulates and trick our ear of hearing it
- Presumably can achieve a lot of interesting effects, like spatial sound

Example: