Getting a weired behavior when windowing an audio signal
It turns out that the windowing function that is used performs by default "Zero-Phase Zero-Padding" on the input signal.
You can disable this feature by setting the zeroPhase parameter to False as follows:

w = std.windowing(type='hamming',
                  size=len(audio_pool['frames.actual-frames'][22]),
                  normalized=False,
                  zeroPhase=False)