Am Donnerstag, den 23. März 2017 um 10:59:16 Uhr (-0300) schrieb Alexandre Torres Porres:
the input is a sinusoid
That's the problem: If the size of the analysis window is sufficiently large compared to the frequency of a static sinusoid You can't really expect any difference in the rms values if the window gets shifted. As stated before, no overlap-add is performed.