Self-Oscillating Vocal Fold Models Coupled to 3D-Printed Vocal Tracts, Part II: Aerodynamics and Kinematics with and without Semi-Occluded Vocal Tract (SOVT) Tubes at Constant Low-Flow Conditions

Self-oscillating vocal fold models (SO-VFMs) are often utilized in voice research as such models retain many of the dynamic aerodynamic features observed in human phonation. A previous companion paper (MS1) investigated the effects of semi-occluded vocal tract (SOVT) tube extensions on aerodynamic threshold measures in physical SO-VFMs coupled to 3D-printed magnetic resonance imaging (MRI)-based vocal tract models. The current research extends that research by investigating the presence of airflow resistant tubes at constant low upstream flows on glottal aerodynamics and kinematics. Controlled experimental laboratory study. MRI-derived 3D-printed vocal tract models of a healthy vocally trained adult male producing the vowels /ɑ/ and /u/ were coupled to multilayered SO-VFMs that yield phonatory aspects analogous to human phonation. A set-up similar to the previous study (MS1) was used; however, the current experiment included independent measurement of subglottal and supraglottal pressures and measurement of glottal kinematics via a flexible fiberoptic endoscope with videostroboscopy. Two silicone models in “tube on” and “tube off” states were examined at a constant airflow just above phonation threshold flow onset . The presence of airflow resistant tubes at constant upstream flows tended to reduce mean transglottal pressure, increase sub- and supra-glottal pressure, and reduce f o . Evidence was observed indicating a possible “transitional region” relative to tube inner diameter (ID) between approximately 5.9 mm and 7.5 mm. Tubes with IDs above the transition region had wider maximum glottal widths when the tube was present and narrower maximum glottal widths when the tube was removed. Tubes with widths below the ID transition region had narrower maximum glottal widths when the tube was present and wider maximum glottal widths when the tube was removed. Flow-resistant tubes impact glottal aerodynamics, acoustics, and kinematics during SOVT exercises potentially via an aerodynamic glottal widening effect .