Study of characteristics of aperiodicity in Noh voices

The feasibility of representing the excitation source characteristics in expressive voice signals by an aperiodic sequence of impulses in the time domain is examined in this paper. In particular, the aperiodic components of excitation of expressive voices, like the Noh voice, are examined in some detail. The aperiodic component is extracted from the speech signal using a modified zero-frequency filtering method, and it is represented using a sequence of impulses with amplitudes corresponding to the relative strength of excitation around each impulse. The spectral characteristics of the aperiodic sequence show subharmonics and harmonics of the fundamental frequency corresponding to pitch. The effects of aperiodicity are examined using spectrograms and saliency plots of synthetic amplitude and duration (i.e., frequency) modulation of sequences of impulses.