When you learned about the Doppler Effect in high school physics
class—the wave frequency shift that occurs when the source of
the wave is moving, easily illustrated by a passing
ambulance—you probably didn't envision it helping control your
computer one day. But that's exactly what a group of researchers
are doing at Microsoft Research, the software giant's Redmond,
Washington-based lab. Gesture control is becoming increasingly
common and is even built into some TVs. While other motion-
sensing technologies such as Microsoft's own Kinect device use
cameras to sense and interpret movement and gestures, SoundWave
does this using only sound—thanks to the Doppler Effect, some
clever software, and the built-in speakers and microphone on a
laptop. Desney Tan, a Microsoft Research principal researcher
and member of the SoundWave team, says the technology can
already be used to sense a number of simple gestures, and with
smart phones and laptops starting to include multiple speakers
and microphones, the technology co