Interpretation of Ultrasonic Signals in Terms of Phase Difference of Vocal Fold Vibration
Sandra L. Hamlet · The Journal of the Acoustical Society of America · 1972
The amplitude variation of a continuous wave ultrasonic signal received through the larynx during phonation at low pitches suggests that the signal may contain information on the phase difference between vibration of the upper and lower edges of the vocal folds. Vertical placement of transducers was systematically varied during sustained phonation at constant vocal frequency and intensity. It was anticipated that the time relationships between ultrasonic and speech signals recorded simultaneously would change as the ultrasonic beam passed from predominantly through the upper edge to predominantly through the lower edge of the vocal folds. Transducers with different beam characteristics were tried on several speakers, but good results were obtained only for a male with a bass voice, using a narrow 5-MHz beam. Data from this subject showed the lower edge of the vocal folds closing slightly before the upper, and the lower edge opening before the upper also, but with a greater phase difference on opening. Results indicate that potential exists for obtaining information on phase difference in vocal fold vibration with a continuous wave ultrasonic technique, but more work needs to be done on determining the optimum transducer characteristics. [This investigation was supported by NIH Grant DE 00248-02.]