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I am curious to know the relation between the 16-bit amplitude values in the PCM-encoded signal and the values inside the corresponding spectrogram. I am using Scipy reading a 44100-sample rate song:

from scipy import signal
from scipy.io import wavfile


sample_rate, samples = wavfile.read('some_song.wav')
freq, times, spectrogram = signal.spectrogram(samples, sample_rate, window='hamming',
                                                             nperseg=4410, noverlap=0)

The integer values of samples (in my song) is [-15039, 16432] which I interpret as the relative amplitude level at the particular sample.

However, the integer values of the spectrogram ranges from [0, ~16.7 million]

Can someone explain the relation between those intervals? I guess they're both saying something about the amplitude.

Thanks

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Spectrogram contains magnitude values only, that explains why the values start at 0 instead of some negative value. And scipy seems to calculate it with 24bit accuracy, where $2^{24}\approx 16.7\cdot10^6$.

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