Extracting the fundamental frequency of a .wav file

I have a .wav file, which I read with wavread and later do the fft.

If Y=fft(y,N), being y the vector with the samples of the .wav file and Y the fourier transformation of y.

How can I make a relation between the frequencies and the samples of Y? I want to get the frequency in wich Y has the highest value.

Thanks.

Answer 1

[Wayne King]

Here is an example you can modify with your input y

For even length y:

    Fs = 1000;
    t = 0:0.001:1-0.001;
    y = cos(2*pi*100*t)+randn(size(t));
    ydft = fft(y);
    freq = 0:Fs/length(y):Fs/2;
    ydft = ydft(1:length(y)/2+1);
    plot(freq,abs(ydft))
    [maxval,idx] = max(abs(ydft));
    freq(idx)  %this is frequency corresponding to max value

For odd length y

    t = 0:0.001:1;
    y = cos(2*pi*100*t)+randn(size(t));
    ydft = fft(y);
    freq = 0:Fs/length(y):Fs/2;
    ydft = ydft(1:floor(length(y)/2)+1);
    [maxval,idx] = max(abs(ydft));
    freq(idx)  %this is frequency corresponding to max value

[Rosano Rosano Sánchez]

Thanks Wayne, it was really helpfull :)

[Marco Macedo]

Hello, i´m really late xD but how can i extract the frequenct of the first peak? that is the fundamental frequency

[Mohit Motwani]

what if I compute an n-point fft like

ydft = fft(y, 2048);

Should I still use this line?

ydft = ydft(1:2048/2);