I want to build a guitar tuner app for Iphone. My goal is to find the fundamental frequency of sound generated by a guitar chord. I have used bits of code from aurioTouch sample provided by Apple to calculate frequency spectrum and I find the frequency with the highest amplitude . It works fine for pure sounds (the ones that have only one frequency) but for sounds from a guitar chord it produces wrong results. I have read that this is because of the overtones generate by the guitar string that might have higher amplitudes than the fundamental one. How can I find the fundamental frequency so it works for guitar strings? Is there an open-source library in C/C++/Obj-C for sound analyzing (or signal processing)?
What do you want to identify in a chord ? It can have many frequencies... You can choose to find the lowest, or the highest amplitude, or a selection of the 3 or 4 highest amplitudes and try to identify possible chords for them, but its really a tough problem.
How to compute fundamental frequency?
Can you post your code?
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