Oh, this is wonderful.

Air Theremin turns your phone or laptop into a musical instrument you play by waving your hands around in empty space. No controller. No keyboard. No touching anything. Just grant the browser access to your camera, hold up both hands, and suddenly you’re performing in that wonderfully eerie, swooping musical territory traditionally occupied by mad scientists, 1950s flying saucers, and Clara Rockmore.

And it actually understands your gestures.

Spread your hands apart and the sound gets louder. Raise them and the pitch climbs. Bring your palms together and it falls silent. Tilt your hands like a seesaw and you get vibrato. Lean backward and the sound darkens and acquires more room and reverberation. It’s an instrument whose control surface is simply the space around your body.

On a phone you can switch to gyroscope mode and play by tilting the device instead: left-right controls volume and forward-back controls pitch. If neither camera nor motion sensor is available, you can even drive the thing with a mouse.

Then things get more elaborate. Choose sine, triangle, warm or reed-like waveforms; add reverb, vibrato, tremolo or echo; snap pitches toward musical notes; and record the resulting extraterrestrial aria.

The original theremin, invented by Léon Theremin more than a century ago, was already an uncanny proposition: an electronic instrument played without touching it. Air Theremin takes that idea one step further and removes the instrument itself. What remains is gesture, space and sound.

It takes about five seconds before you stop regarding this as a clever web demo and begin waving your arms around like an orchestra conductor attempting first contact with Alpha Centauri.

Go play it: theremin.bizibah.com