A Synthetic, Self-Oscillating Vocal Fold Model Platform for Studying Augmentation Injection

Objective To design and evaluate a platform for studying the mechanical effects of augmentation injections using synthetic, self-oscillating vocal fold models. Study Design Basic science. Methods Life-sized, synthetic, multilayer, self-oscillating vocal fold models were created that simulated bowing via volumetric reduction of the body layer relative to that of a normal, unbowed model. Material properties of the layers were unchanged. Models with varying degrees of bowing were created and paired with normal models. Following initial acquisition of data (onset pressure, vibration frequency, flow rate, and high-speed image sequences), bowed models were injected with silicone that had material properties similar to those used in augmentation procedures. Three different silicone injection quantities were tested: sufficient to close the glottal gap, insufficient to close the glottal gap, and excess silicone to create convex bowing of the bowed model. The above-mentioned metrics were again taken and compared. Pre- and post-injection high-speed image sequences were acquired using a hemilarynx setup, from which medial surface dynamics were quantified. Results The models vibrated with mucosal wave–like motion and at onset pressures and frequencies typical of human phonation. The models successfully exhibited various degrees of bowing which were then mitigated by injecting filler material. The models showed general pre- to post-injection decreases in onset pressure, flow rate, and open quotient and a corresponding increase in vibration frequency. Conclusion The model may be useful in further explorations of the mechanical consequences of augmentation injections.