Fundamental frequency perturbation observed in sustained phonation.

The middle segments of sustained phonations of /i/, produced by six male adults at fo's ranging from 98 to 298 Hz, were examined for cycle-to-cycle frequency perturbation. The voice samples were analyzed by a peak-picking fo analysis program (Horii, 1975). The results showed that, between 98 Hz and 210 Hz, mean jitter size decreased as the fo increased, whereas the corresponding jitter ratios remained relatively constant. Above about 210 Hz, mean jitter remained relatively constant and, consequently, the jitter ratio increased as fo increased. The problems of temporal resolution for vocal jitter studies, vowel-dependent jitter magnitude characteristics and various perturbation measures are discussed.