Smartwatch algorithm tracks hand’s movement where speaker emits inaudible sonar bouncing off hand/ microphone captures echoes

https://www.eurekalert.org/news-releases/1122920

"WatchHand's real-time machine-learning translates echos into 3D hand’s gestures, typing movements, wrist rotations... works well in noisy environments/ struggles if user walking/ running as arm movement interferes with echoes... control home environments/ wheelchairs/ AR/ VR, type email via micro-gestures tracked by already owned smartwatch, with no cameras or bulky gloves required... local, so personal data isn’t shared"