Aftertouch utilises the 3D Touch technology in the latest iPhones to capture those elusive qualities of velocity and pressure. As with other touch screen controllers you can use a tap for note on and then glide forwards or backwards, or side to side, to affect modulation or pitch. This is the first controller app to be able to offer velocity and pressure as well.
Aftertouch has its own phase modulation synthesizer built in. This gives you a perfect demonstration of what sort of control is on offer. Outside of that you can route it internally or externally to other music apps or your DAW or MIDI instrument. The X, Y and Z (pressure) parameters can be mapped to any MIDI CC number. Pitch and modulation might be obvious contenders, but how about filter cut-off and reverb depth, or mapping pressure to delay feedback. There are all sorts of possibilities.
The app itself is really very simple. It’s a grid of 20 pads. Each is a note and you tap it and slide and push to generate the MIDI control data. The colour ring in each pad changes depending on the velocity and that’s about it. It could be a lot more complex and perhaps there’s more to come in future updates but for now it’s all too easy. I imagine that the synthesizer side of it will get a bit ignored. It’s the use with other synths and apps that makes it really interesting.
Of course it’s all dependant on the 3D Touch. If you don’t have an iPhone 6 or 7 then you can still use the X and Y facilities, but not the touch or velocity. Currently Bitwig on the Microsoft Surface holds the crown for the most expression use of a touch screen where it incorporates the Surface Pen to generation pressure data. But Aftertouch’s remarkable use of the technology and opens up touch control to a whole new world of MPE and MIDI control. Multi-dimensional Polyphony Expression (MPE), as we all know, is what we call 5 dimensional, polyphonic MIDI control. It’s what’s found on the ROLI keyboards and the LinnStrument. If the forthcoming new iPads incorporate 3D Touch then this is going to bring in a new generation of expressive touching.