After investigating the guitar tutor software on and off for about 3 months, I’ve decided to go in a different direction. The biggest hurdle is lack of time, and the small delay between the time the note is struck and the time the signal is recognizable as the required note. You could get by with faking it, and not showing the user acutal real-time results. Look up automated music transcription and you’ll find algorithms out there. 

In any event, I’ve started a new project developing a musical theory app for the iPhone. It’s called uSightRead and you can follow it’s progress on its own website. This is somewhat similar to the guitar game, but without the pesky need to determine the notes from a real guitar. Hopefully it’ll be a big hit.