Vocal fold dimensions in professional opera singers as measured by means of laser triangulation.

A new laser triangulation technique was used to measure vocal fold length and width in 27 professional opera singers. The singers belonged to different voice register categories: soprano, mezzo, tenor, and bass/baritone. High-speed recordings were made during glissandos from each singer's speaking fundamental frequency (SFF) up to the highest frequency for which it was possible to place the laser spot on the vocal folds. Vocal fold length and width were measured at the singers' SFF and then at two or three times the SFF, and for some singers at four times the SFF. In addition, measurements were also made at C4 (260 Hz) for all singers. The results confirmed that the bass/baritone group had significantly longer vocal folds than the soprano group; also, males have significantly longer vocal folds than females. Measured values for vocal fold width were significantly larger for the bass/baritone group compared with all other groups. A measured strain parameter showed different patterns of vocal fold elasticity with increasing pitch. The results suggest that although vocal fold length and width contribute to a singer's voice register category, there seem to be also other parameters that are essential for this distinction.