A computational study of systemic hydration in vocal fold collision

Area of Science:

• Biomechanics
• Voice Science
• Computational Fluid Dynamics

Background:

• Phonation involves complex mechanical stresses within vocal fold (VF) tissues.
• These stresses influence VF tissue hydration, a critical factor for voice health.
• Understanding the interplay between mechanical forces and tissue hydration is essential for diagnosing and treating voice disorders.

Purpose of the Study:

• To investigate the effects of phonation-induced mechanical stresses on vocal fold tissue hydration.
• To quantify the relationship between vocal fold dynamics (vibration, collision) and interstitial fluid movement.
• To model the poroelastic behavior of vocal fold tissue under realistic phonation conditions.

Main Methods:

• High-fidelity, fully 3D numerical computations were performed.
• A segregated solver approach utilized commercial solvers for VF tissue and glottal airflow.
• Tissue viscoelastic properties were derived from a biphasic formulation, considering different fluid volume fractions.
• Poroelastic assumptions were used to estimate interstitial fluid movement from hydrostatic stress gradients.

Main Results:

• Computed VF dynamics measures (airflow velocity, deformation, vibration frequency, contact pressure) aligned with experimental data.
• Mechanical stresses were analyzed in relation to VF vibration and collision.
• Interstitial fluid movement was estimated based on hydrostatic stress gradients.

Conclusions:

• Vocal fold deformation and vibration generally increase tissue hydration.
• Vocal fold collision, however, leads to a reduction in tissue hydration.
• These findings highlight the dynamic regulation of vocal fold hydration by phonation mechanics.