C/C++/Obj-C Real-time algorithm to ascertain Note (not Pitch) from Vocal Input
Check the accepted answer on this link.
I have scoured SO for an answer to this problem, and this is the most useful resource I have found.
It appears that Performous uses this algorithm, but it's hard to make out from the Performous code
EDIT: I have finally managed a working solution. e-mail me if interested sunfish|gmail|c0m