The STFT analysis breaks down the glottal signal category into overlapping segments and shapes each segment with an envelope: X ( m , k ) = ??? m = - ??? ??? ??? ( ?? m ??? h n - m ) ??? ??? - j ??? ( 2 ??? ?? / N ) ??? k ??? ??? m where Xm is the input signal, hn???m is the time-shifted window, n is a discrete time interval, k is the index for the frequency bin, N is the number of points in the s