26. The method according to claim 25 , wherein one or a plurality of variances of said spectral centroid, of said spectral flux, or of said spectral roll off are computed.
26. The method according to claim 25 , wherein one or a plurality of variances of said spectral centroid, of said spectral flux, or of said spectral roll off are computed. 28. The method according to claim 26 , wherein said variances are respectively taken as parameters.