The amplitude - Frequency plot would go something like this:
L = size(y,1);
Fn = Fs/2;
FTy = fft(y)/L;
Fv = linspace(0, 1, fix(L/2)+1)*Fn;
Iv = 1:numel(Fv);
There could be two channels in the .wav file. This will plot both of them in the same plot. Note that ‘Fn’ is the Nyquist frequency, ‘Fv’ is the frequency vector, and ‘Iv’ is the index vector for the plot or other analyses.
I do not have your .wav file so I could not test this with it. It should work.