So, the above device (Arduino powered again) is intended to detect (via a microphone) different kinds of taps on a surface, and convert them into midi messages. It’s intended use is for laying down Midi drum tracks quickly and easily, without the need for expensive V-kits or drum pads. However, there are few problems with it at the moment – it works, but not too well. It may only be about 95% accurate at detecting the difference between two different instantaneous sounds, and that gets worse the more sounds you add to it’s memory. I think the concept is good, but it may need to be realised on something more powerful than an Arduino! I will be bringing it along to the MOSI mini maker fair this week, so if you want to have a go, come on down.