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SoundWave: Using the Doppler Effect to Sense Gestures
Hraness wrote this summary from a saved copy of the source. Quotations are taken word for word from the source.
gist
SoundWave turns a laptop's ordinary speaker and microphone into a Doppler gesture sensor. The system plays an inaudible tone, measures frequency shift when the hand reflects it, and recovers in-air gestures without dedicated depth cameras or IR hardware. The CHI 2012 note describes the detection algorithm, shows several gesture families, and reports an informal cross-device, cross-person robustness check on commodity machines.
ideas
- Reuse the audio I/O you already ship. Speaker plus microphone can double as a motion sensor, so gesture support need not wait on new silicon.
- Doppler shift is the signal. An inaudible carrier reflects off a moving hand; the microphone hears the frequency offset and that offset encodes motion.
- Gestures become classification over shifts. Once frequency change is measured, familiar in-air motions can be inferred without vision.
- Robustness is informal but cross-cutting. The note evaluates the approach across devices and people rather than claiming a calibrated production sensor.
quotes
“We present SoundWave, a technique that leverages the speaker and microphone already embedded in most commodity devices to sense in-air gestures around the device.”
“we generate an inaudible tone, which gets frequency-shifted when it reflects off moving objects like the hand.”
“We measure this shift with the microphone to infer various gestures.”