Theremin I/O: An App That Turns Your iPhone Into A Hands-Free Instrument

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Theremin I/O: An App That Turns Your iPhone Into A Hands-Free Instrument

Music apps have been around for the iPhone for nearly as long as the touchscreen device have existed. First it started with simple keyboard and guitar simulators—and now we’ve got fairly advanced recording, remixing, and sequencing apps that are almost as powerful as their professional counterparts for Mac or Windows. The theremin, however, is one of the strangest musical instruments ever devised—it plays music unlike anything else by detecting the motion and position of your hands as you wave them around the instrument—and now there’s an app for that.

At first it might not make sense—the iPhone’s functionality as a touch-centric device doesn’t exactly seem like a good fit for simulating an instrument that you don’t touch. But the genius thing about the Theremin I/O app lies in how it uses the iPhone’s rear-facing camera to replicate the functionality of the quirky instrument.

When you start the Theremin I/O app, it drops you in with a basic tutorial on how to turn the digital instrument on and from there you’re free to play around. The first thing to do is calibrate it to the room’s lighting because the app plays music based on how bright the camera image is. After that flicking the orange switch on the upper left will turn on the music.

Once it’s on, the digital rendition of the already digital instrument will turn on the iPhone’s flash and show whatever the camera sees trough the round, porthole shaped window on the upper right corner. From here you can basically just keep waving your hand past the lens to start striking up some notes or if you’re beaming the phone’s flash against a surface, simply shaking the handset works just as well.

Ideally you’ll want to play in the dark, otherwise the fake theremin will keep playing a low autotuned warble, which to some could be great for a backing track too. The idea is to just keep playing around by waving some fingers past the camera or to start moving you hand closer to the camera. You’ll start figuring out that Theremin I/O creates a constant tone as long as part of the image is white—the brighter it is on the screen, the louder the music will become in turn.


On top of the basic theremin instrument, the app can also has extra options to play notes like the space horn sounding Wawa, an electric guitar, and even the robot Wall-E. Tapping on the lower tabs meanwhile will bring you to other pages that will let you change the way the instrument sounds.

The Sound tab of course will change the way it sounds based on the instrument you choose and the two knobs. The Sensor range settings will change how wide the scale of octaves the instrument scale should span the pitch limits depending on how close you bring your hand. Meanwhile, the Harmony tab has a set of deeper controls that changes how loud every note is in octaves—lower levels will produce dulcet tones while going higher on the levels will create something closer to screeching notes meant for dog ears.

Theremin I/O is perhaps one of the most interesting musical instrument apps on the iOS app store simply because it doesn’t have you stroking the touchscreen. It’s a bit silly of course, and if you try to play it in public you’re more likely to annoy your captive audience or just look plain crazy. For someone with no musical background such as myself it’s really just a short diversion, but it proves to live up to the reputation of the experimental and zany real life instrument.

Theremin I/O is an iOS app, developed by FFFF00 Agents AB. It can be download in the App Store for $1.99.

Kevin Lee is a freelance writer who types all day and listens to his ever-expanding music library. Follow Kevin Lee on Twitter at ">@baggingspam