Objective: Self-oscillating vocal fold models (SO-VFMs) (Thomson, 2024) realistically simulate complex physical aeroacoustic phenomena, allow for precise control over geometric parameters and material properties, and allow for examination of vocal kinematics, acoustics, and aerodynamics. Static and computational models have investigated the effects of geometric variables such as inferior and superior vocal fold surface angles (Li et al., 2006a), glottal angle (Li et al., 2006b), glottal entrance (Li et al., 2012) and exit (Scherer et al., 2001) radii, and vertical glottal duct length (Li et al., 2018, 2021) on intraglottal pressures and phonation threshold pressure (PTP). However, the effects of the above M5 geometric variables on phonatory outcome measures such as PTP have not yet been empirically studied in a (silicone) physical vocal fold model. Such research is essential to validate computational modeling results and to examine the effects of these previously unexamined vocal fold model geometric variables for purposes of model optimization (i.e., to increase model realism) as SO-VFMs often have higher than typical human onset pressures (May & Scherer, 2023; Thomson, 2024)

Methods/Design: The M5 vocal fold shapes (Scherer et al., 2001b) have been widely used in mathematical and physical modeling of the human voice (Thomson, 2024). In the current study, modifications to the M5 geometry will be explored using physical single-layer isotropic silicone SO-VFMs. The effect of inferior and superior vocal fold surface angles, entrance and exit radii, intraglottal convergence/divergence angle, vertical vocal fold thickness, and vocal fold length on glottal aerodynamics (PTPs), acoustics (f0), and kinematics (e.g., max glottal width, OQ) will be experimentally explored using a bench set-up similar to May & Scherer (2023) but without a vocal tract. Three levels of each variable within the range of expected human values (Nanayakkara, 2005) will be examined and replicated in two identical pairs of vocal fold models per experimental condition. Adduction level and material properties (e.g., Young’s moduli) will be held constant. Results from the various geometric conditions will be examined to determine the optimal condition for reducing PTP.

Results: Results of prior research by Li et al. (2006a, 2006b, 2012, 2021), Scherer et al. (2001a), and Zhang (2023) will be tested using a physical silicone SO-VFM. Prior studies in our lab using SO-VFMs have successfully examined the relationship between vocal tract constrictions (May & Scherer, 2023) and SOVT tube geometry (May, Scherer, & Meyer, in review) and aerodynamic threshold measures.

Conclusions: The current laryngeal modeling work seeks to improve on the methodology used in prior research to optimize the geometry of the M5 vocal fold model to yield reduced PTPs that more closely replicate human phonatory conditions. Based on the success of this prior work, the probability is high that the current project will succeed methodologically and provide insight into the relationship between vocal fold geometric variables and glottal aerodynamics.