ULTRASONIC DOPPLER MONITORING OF VOCAL-FOLD VELOCITY AND DISPLACEMENT

We have compared ultrasonic Doppler signals from the region of the vocal folds with the actual motion of the folds in order to determine the reliability of using the ultrasonic Doppler system suggested by Minifie et al. [J. Acoust. Soc. Amer. 43, 1165 1169 (1968)] for monitoring the folds during phonation. Frame by frame analysis of high speed split image laryngeal film showed that velocities and displacements calculated from the Doppler signals do not always correlate with the motions of the folds. Significant errors were found in the timing, magnitude, and general shape of the calculated velocity and displacement pattern. Furthermore, the relationship between recognizable Doppler frequency patterns and the corresponding motions of the folds was both inconsistent and ambiguous. Because of this ambiguity, the Doppler system proposed by Minifie et al. has proven unsatisfactory as a continuous monitor of vocal fold velocity and displacement. Tests of this Doppler technique using a flat surface phantom moving at typical vocal fold displacement and frequencies resulted in an accurate correlation between the velocity and displacement patterns calculated from the Doppler signal and those measured from the film. The complex motions of the folds during phonation is postulated as the primary reason for the unreliability of this Doppler technique in vivo. © 1969, Acoustical Society of America. All rights reserved.