In this paper, we study the significance of aperiodicity in the pitch-perception of expressive voices such as Noh voice and laughter signals. The excitation source characteristics in the production of these signals is represented in terms of a sequence of impulses. The impulse sequence is derived from the acoustic signal using a modified zero-frequency filtering method. The time intervals between successive impulses and relative amplitudes of impulses are related to the presence of subharmonics and pitch-perception in expressive voices. The role of aperiodicity and subharmonics in the perception of distinct voice quality of expressive voices is examined. The significance of aperiodicity is also analysed by synthesis, using two synthetic AM/FM sequences for excitation. Saliency is used as a measure of pitch perception. The F0 extraction using this pitch perception information for expressive voices is also demonstrated.