Direct measurement of glottal volume velocity using high-speed, stereoscopic, particle imaging velocimetry
David A. Berry, Juergen Neubauer, Zhaoyan Zhang · The Journal of the Acoustical Society of America · 2006
Despite its central importance as the glottal source in several long-standing models of voice production, the glottal volume velocity signal has been relatively little studied. In particular, few direct measurements of the glottal volume velocity signal have been made. One common method for estimating the glottal volume velocity signal has been linear inverse filtering of the oral acoustic output. However, a major assumption of linear inverse filtering, and of the linear source-filter theory of speech production in general, is that the glottal source and the vocal tract are independent of each other. The accuracy of this assumption has been questioned, particularly at extremes of fundamental frequency and intensity. In order to test the limits of linear inverse filtering, direct, instantaneous measurements of glottal volume velocity have been made using high-speed, stereoscopic, particle imaging velocity on a self-oscillating, physical model of vocal-fold vibration. These direct measurements are contrasted with results from linear inverse filtering.