Spectral centroid 6 harmonics: f0 = 100Hz E.g. 1: Amplitudes: 6; 5.75; 4; 3.2; 2; 1 [(100*6)+(200*5.75)+(300*4)+(400*3.2)+(500*2 )+(600*1)] / 21.95 = 265.6Hz.