Find and plot peaks within range of FFT

Hey guys,

I am given a wav file of a guitar playing the G,B and E notes simutaneously and I need to find the fundamental frequencies of the 3 notes. The standard fundamental frequencies for these three notes are 196 Hz, 246.9 Hz, and 329.6 Hz. I have read the signal and plotted the fourier transform but I am having trouble finding the peaks of the transform and plotting them on the same graph. I was wondering if it was possible to find the peaks within the range of these frequencies and then plot those peaks on the same graph of the fourier transform as I think that would give me the fundamental frequencies. Below is my code and any help would be appreciated.

https://pastebin.com/42aL69k2

Here is the plot of the fourier transform of the wav file I am reading.

Answer 1

[Star Strider]

The easiest approach would be to use the Signal Processing Toolbox findpeaks function. It has a number of name-value pair argument options that should allow it to do exactly what you want.