I realise that this isnt a quick and easy project, but since i'm struggling to come up with ideas of what to make next, I figured ill give it a try.

I have had some experience with the things rswain mentioned including interrupts, counters, comparators and some basic zero-crossing detection. The fun bit is going to be getting all of those things to work together to produce a result.

I feel pretty confident about the coding side of things (or at least as confident as you can be when trying to tackle a tricky problem). Where my knowledge is going to let me down is the analogue electronics side. As soon as things are digital im fairly comfortable.

Does anyone have ideas on how best to amplify the mic signals and convert them to square waves? I think this is where I will struggle the most.