Microsoft Research has teamed up with researchers from the University of Washington to develop a sonar-based Kinnect-like motion sensing system based only on the speakers and microphone fitted in laptops.
The system depends on the Doppler effect, producing inaudible tones between 18 to 22KHz. The microphone picks up the shifted frequencies to sense movement of objects in front of the speakers in a sonar-like system Microsoft is calling SoundWave.
In a video on Microsoft's Research website, the researchers showed how it was possible to sense gestures including two-handed gestures. A demonstration even shows one researcher playing a game of Tetris simply by making gestures in front of the laptop.
Another simple but obvious application is turning on a laptop display when a user approaches the device. Microsoft also demonstrated SoundWave and hand gestures working in a noisy environment, showing that the system still worked on a laptop in a coffee shop.
Microsoft presented SoundWave at the ACM SIGCHI Conference on Human Factors in Computing Systems that took place in Austin, Texas over the last few days. A short paper with more technical details is available here (pdf).