Some Statistical Characteristics of Voice Fundamental Frequency

Abstract

Distributional measures such as mean, median, standard deviation, 90% range, and 50% range of fundamental frequency have been often used to characterize voices. This study reports behavior of such statistical measures for each of six talkers as a function of sample size (from 3.6 up to 200 sec). Fundamental frequencies were obtained by a computer program that used a peak-picking method. The results showed that, for each script reading hy a given talker, the standard deviations of the means converge fairly quickly—that is, to within about 2 Hz of the total mean at a sample size of about 1 min. However, when all the various readings from even a single talker are used to get the total mean, the convergence was much slower, indicating that differences among the scripts and day-to-day variations in repeated readings are significant and must be taken into account when interpreting statistical measures of fundamental-frequency variation. Median convergence behavior was the same. Implications of these findings to studies of normal and disordered speech are discussed. [This research was supported in part by the Air Force Cambridge Research Laboratories.]