Using hamming window for Paraformer frontend.

[TeaPoly]

The default window in the Paraformer frontend is hamming. We can find more details here. However, the default window in kaldi.fbank is povey, as specified here. This different window maybe a little mismatch. As mentioned in line 44 of this document:

"povey" is a window I made to be similar to Hamming but to go to zero at the edges, it's pow((0.5 - 0.5cos(n/N2*pi)), 0.85) I just don't think the Hamming window makes sense as a windowing function.