Applies Hanning window to Src. Window functions are applied to the signal prior to conversion to frequency domain with the FFT algorithm, to reduce the spectral leakage. Their side-effect is a lower frequency resolution. Hanning window is very widely used and sufficient for most applications. The equation for the Hanning window can be found in [1] p. 249: 

w[i] = 0.5*(1-cos(2*Pi*i/(n-1)) 

0 < i < n-1 

References:  

[1] Digital signal processing, Vinay K. Ingle and John G. Proakis, Brooks-Cole, 2000.

CosineTappered, Kaiser, SignalWindow, Hamming

Hanning Method