Biomechanical and Vibratory Characterization of Synthetic Vocal Fold Phantoms Mimicking Pathological Conditions

Abstract

This study investigates how benign vocal fold pathologies alter vibratory and biomechanical behavior through an integrated computational and experimental framework. Silicone phantoms representing healthy vocal folds, sulcus vocalis, and vocal fold polyps were fabricated from room-temperature vulcanizing silicone, whose stiffness was tuned to match the volume-averaged modulus of human vocal fold tissue. Each phantom was characterized using four complementary methods—chopper-modulated airflow, optical-lever and laser Doppler vibrometry self-oscillation, and non-contact magnetic-impulse excitation—and compared with finite-element (FE) eigenfrequency and harmonic-response simulations. The fundamental frequency followed the ordering <inline-formula> <tex-math notation="LaTeX">$f_{p} \lt f_{h} \lt f_{s}$ </tex-math></inline-formula> in the FEM and in the three methods that resolve it: chopper modulation, optical lever, and LDV. These shifts reflect the combined effect of lesion mass and lesion geometry, not mass alone. For the matched 3.40-kPa FEM and modulated-vibration comparison, the fundamental-frequency deviations were 4.7%, 0.0%, and 12.6% for the polyp, healthy, and sulcus cases. The rippled surface of the sulcus phantom further amplified higher-frequency modal content, while the low-to-high energy ratio resolved the three conditions in the inverse order. The predicted shifts (<inline-formula> <tex-math notation="LaTeX">$f_{p} \approx 0.9{\,}f_{h}$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$f_{s} \approx 1.1{\,}f_{h}$ </tex-math></inline-formula>) fall within clinically reported ranges. A viscoelastic sweep preserved this ordering for all three single-layer geometries. This work characterizes idealized phantoms; clinical evaluation, surgical planning, and outcome prediction remain future goals.