Perturbation in Gci's and Speech Quality for Pitch Synchronous Synthesis

In pitch synchronous speech synthesis the analysis/synthesis of the speech is done at each glottal closure instant (GCI). The errors in estimation of GCI's affect the quality of the synthesized speech. The effect of random perturbations in the GCI's, obtained from the speech and from glottal signal from an impedance electroglottograph using Childers and Hu's algorithm on the quality of speech synthesized using harmonic plus noise model (HNM), is investigated in this paper. Investigations show that the speech quality is very sensitive to positions of the GCI's. A small perturbation with maximum of 4 % of the local fundamental frequency considerably degrades the synthesized speech. Perturbations above 8 % severely affect quality of the out put speech. GCI's obtained from the glottal signal can afford slightly more perturbation as compared to the GCI's calculated from the speech signal.