Nonlinear dynamical analysis of the vowels in a Korean traditional folk songs

Two kinds of vocalization techniques, strongly pressing vibration and frequ ently pressing vibration, for Seodo folk songs from Korean traditional folk songs were analyzed for four Korean vowels from the viewpoint of nonlinear dynamics. We investigated the power spectrum, the phase portrait, the corr elation dimension, and the second-order Kolmogorov entropy. The power spect ra from the same vowels showed small difference between the two vocalizatio n techniques. On the other hand, the correlation dimension of the time seri es from the frequently pressing vibration turned out to be higher than that of the time series from the strongly pressing vibration. The second-order Kolmogorov entropies of the analyzed time series showed a tendency to becom e positive constants, which is a characteristic of a chaotic system. We als o confirmed the nonlinearity in the dynamics of the time series of the folk sang by using surrogate data.