Tone & Spectrum
Generate a sine tone through your speakers and watch your microphone hear it back. The spectrum below shows the live FFT of whatever your mic is picking up — the tone, room reflections, and ambient noise.
Tone Generator
Microphone Spectrum
Tip: use headphones to avoid feedback. With speakers, you'll see (and hear) the tone loop back into the mic — that's part of the demo.
Doppler Ninja
An inaudible carrier (~19 kHz) plays from your speakers. When your hand moves toward the laptop, the reflected wave comes back shifted up; when it moves away, shifted down (Δf = 2·v·f/c — about 110 Hz per m/s at 19 kHz). The game reads sideband energy on either side of the carrier and uses it to swing the blade. Wave your hand near the laptop to slice the fruit; avoid the bombs.
Best with laptop speakers (not headphones), 10–40 cm hand distance, and a quiet room. Hold still during the calibration bar at the start of each round.