Effect of Variations to a Simulated System of Straw Phonation Therapy on Aerodynamic Parameters Using Excised Canine Larynges

Objectives/Hypothesis Resonance tubes are commonly used in voice therapy. These devices modify supraglottal impedance, potentially decreasing the aerodynamic power necessary for phonation. We modeled phonation with resonance tubes in excised larynges and evaluated the effects of varying tube width, tube length, and flow input on phonation threshold pressure (PTP) and phonation threshold flow (PTF). We hypothesized that the increased vocal economy observed in human subjects and several other models would be observed in excised larynges. Study Design Repeated measures excised canine larynx bench experiment with each larynx serving as own control. Methods Nine conditions were evaluated, namely control, two tube diameters (17.5 and 6.5آ mm), three tube lengths (7.8, 15.0, and 30.0آ cm), and three levels of flow input (80, 114, and 200آ mL/s). Aerodynamic data were collected for 11 excised canine larynges attached to an artificial vocal tract, and results from each experimental configuration were compared with control. Results A significant decrease in average PTP occurred compared with control for the 114- and 200-mL/s flow inputs, 30-cm extension, and 17.5- and 6.5-mm constrictions. Average PTF decreased compared with control for every configuration, although statistically significant changes were only observed for 200-mL/s flow and 6.5-mm constriction. Conclusions Knowledge regarding the effect of vocal tract alterations could be clinically useful in determining the optimal “strawâ€‌ configuration for voice therapy. Further exploration of the relationships among width, length, and flow input could provide theoretical support for the development of new therapies and resonance tube devices.