A new app called AirSynth by Dave Wood takes a fun approach to the Face ID TrueDepth camera system available in the iPhone X series phones. Users simply wave their hands above the phone screen to control the synthesizer, like a pseudo-theremin.

It’s a fun little demo of the kind of data a developer can get from the TrueDepth infrared cameras. Theremin apps already exist in the App Store, of course, but they use the 2D camera to guess at how close a user is holding their hands to the display.

The TrueDepth camera obviously provides much more fine-grained data, as it actually measures depth by using the infrared dot projector and cameras. This means you can control the sound much more precisely.

The app is pretty simple featuring a visualization of the two hands it can see as the backdrop for the app. You just raise your hands in front of the device and sounds start playing. The app bundles several different voice synthesizers, but that’s about the extent of the app.

There are no integrated recording or editing controls, so the app’s utility is somewhat limited once the novelty has worn off.

I can’t shake the feeling that the functionality on offer here will eventually be available as one feature as part of a larger music app, like a new theremin instrument in a future update to GarageBand. GarageBand includes an (admittedly weird) Face ID pitch control already.

AirSynth is compatible with iPhone X, iPhone XS, iPhone XR, and the 2018 iPad Pro. You can buy AirSynth in the App Store for $1.99.