How Do I Get The Values Of A Specific Frequency Range

I have a .wav file, I load it and I get the next spectrogram showing the spectrum in dB http://i.stack.imgur.com/22TjY.png Now I would like to know these values exactly because I

Solution 1:

From the documentation, I gather that Pxx is a simple 2D numpy array.

You're interested in periodograms around 1s. Considering Pxx should have 512 columns and your sample is about 5s long, I'd take a slice somewhere around column 100: periodogram_of_interest = Pxx[:, 100]

Then find the 4 maxima. Unfortunately, each of those 4 frequencies has a finite width, so simply looking for the top 4 maxima will nog be as easy. However, assuming your signal is quite clean, there's a function in scipy.signal that will list all local extrema: argrelmax. You could play with the order argument of that function to reduce your search space.

With the values returned from that function, you could get the frequencies like this: freqs[those_4_indices].