Repeated measures of vocal fundamental frequency perturbation obtained using the Visi-Pitch.

This article reports on a study of intrasubject variability for a measure of vocal fundamental frequency perturbation in a group of young, normal speakers. Measurements of relative average perturbation (RAP) obtained using a Visi-Pitch were examined for the vowels /a/, /i/, and /u/ produced by 25 women and 24 men on two occasions, approximately 1 week apart. Important findings consisted of higher levels of RAP for women than men and greater variability of RAP over the time period studied for women than men. Conclusions include the need for additional normative data regarding the use of the Visi-Pitch for the purpose of examining jitter.