Effect of artificially lengthened vocal tract on vocal fold oscillation's fundamental frequency.
The fundamental frequency of vocal fold oscillation (F(0)) is controlled by laryngeal mechanics and aerodynamic properties. F(0) change per unit change of transglottal pressure (dF/dP) using a shutter valve has been studied and found to have nonlinear, V-shaped relationship with F(0). On the other hand, the vocal tract is also known to affect vocal fold oscillation. This study examined the effect of artificially lengthened vocal tract length on dF/dP. dF/dP was measured in six men using two mouthpieces of different lengths.


RESULTS
The dF/dP graph for the longer vocal tract was shifted leftward relative to the shorter one.


CONCLUSIONS
Using the one-mass model, the nadir of the "V" on the dF/dP graph was strongly influenced by the resonance around the first formant frequency. However, a more precise model is needed to account for the effects of viscosity and turbulence.
Hanamitsu
Masakazu
M
Department of Otolaryngology, Shiga University of Medical Science, Seta, Otsu, Japan.
Kataoka
Hideyuki
H
D000162:Acoustics; D000328:Adult; D000399:Air Pressure; D006801:Humans; D008297:Male; D008875:Middle Aged; D009055:Mouth / Q000502:physiology; D010699:Phonation / Q000502:physiology*; D012143:Respiratory Physiological Phenomena; D012137:Respiratory System; D014732:Vibration; D014827:Vocal Cords / Q000502:physiology*