The speed with which the vocal folds adduct to the midline is considered an important variable in the etiology of some voice disorders and may also be a meaningful indicator of central or peripheral neural dysfunction. It is proposed that the time lag between the rise of the sound pressure (SP) and electroglottographic (EGG) signals, measured at the onset of phonation, provides a useful index of vocal attack time. This report describes the experimental validation of this measure, whereby the SP and EGG signals were recorded synchronously with high-speed videoendoscopy, from which a digital kymogram was generated. It is shown that, after appropriate signal processing, the intersignal time delay provides a potentially useful measure that varies with vocal attack characteristics. The proposed method calls for no invasive procedures and relies on signals that are routinely obtained in most clinical settings. Unlike acoustic "rise time" measures of voice onset, the glottographic measure involves no operator intervention, requires no arbitrary decisions about measurement points, and may be accomplished quickly and automatically on any personal computer.