The new technology uses the Doppler effect
Not one to be outdone by Disney’s any-surface touch interface, Microsoft Research, working with the University of Washington, has developed a Kinect-like system that uses your computer’s built-in microphone and speakers to provide object detection and gesture recognition, much in the same way that a submarine uses sonar.
Called SoundWave, the new technology uses the Doppler effect to detect any movements and gestures in the proximity of a computer. The Doppler effect, if you remember high school physics, is where the frequency of a sound alters depending on your distance from it — the Doppler effect describes the change of a police car siren’s pitch as it moves towards you and then recedes into the distance. In the case of SoundWave, your computer’s built-in speaker is used to emit ultrasonic (18-22KHz) sound waves, which change frequency depending on where your hand (or body) is in relation to the computer. This change in frequency is measured by your computer’s built-in microphone, and then some fairly complex software works out your motion/gesture.
Now, the obvious advantage of SoundWave over a product like Kinect is that it uses existing, commodity hardware; it could effectively equip every modern laptop with a gesture-sensing interface. The flip side, though, is that SoundWave, with a single sound source and microphone, isn’t going to allow for the same kind of accurate, 3D sensing that Kinect, Sony Move, or Wii Motion can provide with cameras and stereo IR sensors.