If you're using pyplot.specgram (i.e. "from pylab import *;
specgram(...)"), note that the plot is in dB, hence the negative
values.
I'm surprised this fact isn't mentioned in the documentation:
http://matplotlib.org/api/pyplot_api.html?highlight=specgram#matplotlib.pyplot.specgram
However, when i
Hi,
If you trace back into the code further, you will see that the Pxx is
computed as X = fft(x), Pxx = X * conj(X) which is real, but the data
type will be complex with a ~0 imaginary part (up to floating point
precision). Thus the Pxx.real is just to ensure that the resulting
data type is real in
