iOS app developer Beep Street wants to turn people’s incessant hand-drumming on tables and desks into actual, listenable music. Its new app, Impaktor, uses the microphone on your iPhone or iPad as an input, then maps the percussive sounds you’re hammering out onto digital instruments. The result is an innovative interface for the app's built-in (and very customizable) synth.

Launch the app and you’ll see six instruments that you can immediately start playing around with — traditional percussion instruments like the metal drum and the tabla. But the app has a lot more to offer, with dozens of preinstalled instruments including lots of electronic and industrial sounds. There's also a rich synth pane that lets you fiddle around with the shapes of the waveforms, add filters, and generally get your hands dirty. And if you want to save your creations there’s a simple sequencer (with quantizing) for building tracks and a recording manager that lets you play back and save your songs so you can export them to your Mac or PC. You can copy the audio within the app as well, which you can use in apps that support pasting from the clipboard, like GarageBand.

Best used wearing headphones without a mic

Because Impaktor uses the microphone as its input you’re going to want to move into a quiet room before you start making music . You’ll also need to use the app with headphones (ideally without a mic), since any ambient sound can be misinterpreted as intentional drumming. This is perhaps the biggest drawback to using a cellphone mic as the interface for a synthesizer, but on the plus side you can set the mic’s sensitivity and add a high-cut filter to cut out background noise. In my admittedly noisy apartment a sensitivity of seven with the filter switched on let Impaktor pick up most of the individual strikes in my finger rolls while still stopping the passing cars from registering.

At $4.99, Impaktor isn’t the cheapest iOS synth we’ve seen, but with its innovative input and wide variety of presets and controls it could be a useful addition to the musician's app arsenal. Impaktor is available now on the iOS App Store.

Ross Miller contributed to this report.