In vivo measurement of laryngeal mucosal wave speed in humans

Measurement of laryngeal mucosal wave speed is potentially important for understanding laryngeal vibration and for guiding phonosurgery. However, measurement of wave speed requires knowledge of distance or phase angle on the vocal folds, and has not been possible in awake patients. A new method permitting such measurements in an office setting is described. This method can be applied using either a calibrated fiberoptic nasopharyngoscope or a calibrated laryngoscope to measure absolute distances in the larynx accurately, reliably, and noninvasively. Wave speeds were measured in one normal male speaker at varying levels of F0 and intensity. Across conditions, measured mucosal wave speed ranged from 0.29 to 1.18 m/s. Wave speeds varied significantly with vocal intensity (r=0.72), but not with F0 (r=0.14). Theoretical implications of these findings will be discussed, along with clinical applications of the new techniques.