Success rate and repeatability of silicone vocal fold model fabrication

Multi-layer synthetic silicone vocal fold (VF) models have been widely used for studying the physics of VF oscillations. These models are commonly fabricated by progressively pouring and curing layers of liquid silicone. However, despite their ubiquity and relatively long history of use in scientific investigations, investigators have reported that measures of oscillatory behaviors can vary widely for the same model/fabrication technique. Consequently, it is questioned how the skill and experience of the individual fabricating the models influence the outcomes. This was investigated by quantifying the fabrication success rate and the oscillatory characteristics of synthetic VF models made by three individuals with different levels of model-making experience; novice, intermediate, and advanced. Subjects were asked to fabricate 12 VF models following a detailed protocol. Models were evaluated at each step of fabrication according to predetermined quality measures. The models that passed were then evaluated by recording their phonation threshold pressure, flow rate, frequency, and glottal area. The fabrication success rate of the novice, intermediate, and advanced users was 0%, 17%, and 67%, respectively. The variability in the kinematic and aerodynamic measures of the successful VF models is also discussed.