Microsoft, along 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.
The technique is similar to sonar and will be handy to allow your pet dolphin to play games. Called SoundWave, the technology uses the Doppler effect to detect any movements and gestures near a computer. In the case of SoundWave, your computer’s built-in speaker is used to emit ultrasonic sound waves, which change frequency depending on where your hand is in relation to the computer. This change in frequency is measured by your computer’s built-in microphone. It is then calculated as a movement by the computer.
The advantage over Kinect is that it uses existing hardware and could give every laptop a gesture-sensing interface. SoundWave doesn’t interfere with any other sounds played by the computer and laptops could come with it preinstalled. Of course your dog would hate it.