Hi, I've written a program inspired by the console game "Guitar Hero" in ChucK. For now it's named "Guitar Zero" unless I think of a better name. Instead of using a special guitar-like controller, it listens to a real guitar/amp via the computer's microphone. The opening screen lets you select parameters and then you get a scoreboard and a fretboard. The program then gives you random notes and detects whether you have played them correctly by using comb filters. So far Guitar Zero is kind of fun and it helps me practice the fretboard. I just got done adding exponentially decreasing time allotment and automatic level increment, but it needs more. I was thinking of adding chords and then possibly whole songs instead of random notes. The thing is, detecting chords might be rather difficult. I could create a chord as an array of notes and have a separate comb filter detecting each note, which is my current plan. Maybe that's the best way to do it. I have the advantage that I know which frequency is the fundamental of each note within a correct chord. So I'm writing partly to share my kewl Guitar Zero program (source posted on the forum), and partly to get your ideas on note and chord detection algorithms. How would you do this task? Thanks, Les Hall (Inventor)