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.

Microsoft SoundWave, measuring the Doppler effect of a moving handWatching the SoundWave video though (embedded below), I am surprised at what has already been achieved with a very simple hardware setup. The most obvious example is a laptop that automatically locks when you move away from it, and unlocks when you return — but it seems that the software is already advanced enough to detect up/down and left/right swipes of the hand. The system’s accuracy, according to the research paper, is between 90 and 100%, even in noisy environments. In one example, some fairly complex hand gestures are used to control the rotation and descending of Tetris blocks. If you added another ultrasonic sound source, and a few more microphones (many laptops already have microphone arrays anyway), SoundWave could probably replicate Kinect very well.

The video also makes clear, however, that waving your hands around — when the keyboard is right there — is a little bit foolish. Still, SoundWave is a freebie — it doesn’t interfere with any other sounds played by the computer (you can listen to music while SoundWave is active), and there’s no reason why laptops shouldn’t come with SoundWave preinstalled. I doubt it will ever reach the accuracy or resolution of camera-based solutions, though, and in all likelihood it won’t be long until we see laptops and smartphones with Kinect built in, anyway. Still, who knows — maybe SoundWave could provide a cheaper option for developing countries, or perhaps it could simply augment Kinect to provide greater accuracy over a wider range of motions/gestures.

[If the video player doesn’t appear, download the MP4 source.]

Read more at Microsoft Research, or read about Disney’s Touche, which turns everyday objects into touch interfaces