Mario A. Svirsky
Kenneth N. Stevens
Melanie L. Matthies
Joseph S. Perkell
Res. Lab. of Electron., MIT, 50 Vassar St., Rm. 36-525, Cambridge, MA 02139
When an obstruent stop consonant is produced, there is an increase in intraoral pressure, and this increased pressure can result in outward movement of the vocal tract walls. Following release of the consonant, the intraoral pressure decreases and the walls are expected to move inward with a time constant that depends on the physical properties of the surfaces. An electromagnetic midsagittal articulometer (EMMA) was used to measure the vertical position of the tongue dorsum during a number of repetitions of five utterances: /ama/, /apa/, /aba/, /ampa/, and /amba/. Results seem to confirm the physical description given above: the average decrease in tongue dorsum position from implosion to release of the consonant was 0.4 mm for /m/, 2.7 mm for /b/, and 1.3 mm for /p/. The smaller movement for /p/ than for /b/ may be due to active stiffening of the tongue during /p/, partly counteracting the effect due to intraoral pressure. These displacements and their rates of movement are consistent with published data on average subglottal pressure, and compliance and resistance of vocal tract surfaces. These data have been used to refine current estimates of physical parameters of articulator surfaces during speech production. [Work supported by NIH Grant No. DC00075.]