Vocal tract area function for vowels using three-dimensional magnetic resonance imaging. A preliminary study.
OBJECTIVE
To assess whether magnetic resonance imaging (MRI) allows the vocal tract (VT) area function to be determined for a normal male speaker.


METHODS
VT shapes were acquired using MRI during sustained production of French points vowels: /i/, /a/, /u/. Cross-sectional areas were measured from a series of planes spaced at intervals of 1 cm along the length of the VT and were used as input in a previously described VT model to simulate the vowels. The first three formant frequencies, F1, F2, and F3, computed from the MRI-measured VT model were compared with subject's natural formant frequencies.


RESULTS
Including piriform sinuses, calculated formants differed from measured formants F1, F2, and F3, respectively, for /i/ by -3.5%, +7.7%, and +27.5%; for /a/ by +11% +19.5%, and -4.3%; and for /u/ by +.9%, +23.4%, and +9.6%. Excluding piriform sinuses, calculated formants differed from measured formants F1, F2, and F3, respectively, for /i/ by -3.5%, +12%, and +28%, and for /u/ by +10.1%, +26.8%, and +13.7% The piriform sinuses were not visualized for /a/ on MRI.


CONCLUSIONS
MRI is a noninvasive technique that allows VT imaging and determination of VT area function for a normal male speaker. Several possible sources of discrepancies are as follows: variability of the articulation, difficulties in assessment of VT wall boundaries, role of the piriform sinuses, and VT length.
Clément
Philippe
P
Department of Otorhinolaryngology-Head and Neck Surgery, Hôpital du Val de Grâce, Paris, France. phclement@wanadoo.fr
Hans
Stéphane
S
Hartl
Dana M
DM
Maeda
Shinji
S
Vaissière
Jacqueline
J
Brasnu
Daniel
D
D000328:Adult; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D010699:Phonation / Q000502:physiology; D010700:Phonetics; D013061:Speech Acoustics; D013067:Speech Perception; D013068:Speech Production Measurement; D014827:Vocal Cords / Q000502:physiology*