Analysis of vocal fold vibration on prosodic events by high speed digital imaging systems

Abstract

A physiological study of prosody is indispensable in terms of the physiological interest as well as of the evaluation and treatment for pathological cases of prosody. We have already reported the study with our high speed digital imaging system [143rd ASA Meeting, 2002] that two major categories (Categories A and B) were found in the ways of changing of vocal fold vibrations at the register change in sustained phonations. In Category A, changes were very smooth in terms of the vibration of the vocal fold vibration. In Category B, changes were not so smooth with some additional events at the register change, such as the anterior–posterior phase difference of the vibration, the abduction of the vocal folds, or the interruption of the phonation. The number of the subtypes for Category B was thought to increase if more subjects with more range of variety are analyzed. In this study, the changes of vocal fold vibration on prosodic events in free talk as the pitch changes were analyzed, using two types of high speed digital imaging system: the one with recording time of two seconds at a rate of 4,500 images of ∼256 pixels per second; the other with a recording time of seven seconds at the same rate with the same spacial resolution as the former. This study showed that high speed digital imaging systems were very powerful tools for the study of prosody.