A Computational Study of Vocal Fold Dehydration During Phonation

Abstract

While vocal fold dehydration is often considered an important factor contributing to vocal fatigue, it still remains unclear whether vocal fold vibration alone is able to induce severe dehydration that has noticeably effect on phonation and perceived vocal effort. A three-dimensional model was developed to investigate vocal fold systemic dehydration and surface dehydration during phonation. Based on the linear poroelastic theory, the model considered water resupply from blood vessels through the lateral boundary, water movement within the vocal folds, water exchange between the vocal folds and the surface liquid layer through the epithelium, and surface fluid accumulation and discharge to the glottal airway. Parametric studies were conducted to investigate water loss within the vocal folds and from the surface after a five-minute sustained phonation at different permeability and vibration conditions. The results showed that the dehydration generally increased with increasing vibration amplitude, increasing epithelial permeability and reduced water resupply. With adequate water resupply, a large-amplitude vibration can induce an overall systemic dehydration as high as 3%. The distribution of water loss within the vocal folds was non-uniform, and a local dehydration higher than 5% was observed even at conditions of a low overall systemic dehydration (<1%). Such high level of water loss may severely affect tissue properties, muscular functions, and phonations characteristics. In contrast, water loss of the surface liquid layer was generally an order of magnitude higher than water loss inside the vocal folds, indicating the surface dehydration level is likely not a good indicator of the systemic dehydration.

Proton density–weighted laryngeal magnetic resonance imaging in systemically dehydrated rats

“…In vivo imaging accounts for homeostatic mechanisms that regulate water content and is a more accurate representation of vocal fold hydration. Wu and Zhang used a computational model to link increased dehydration with increased vibration amplitude, increased epithelial permeability, and reduced water resupply, but there were simplifications and assumptions made within that study as acknowledged by the authors 25 . Hanson et al used a tissue dehydration method of ex vivo systemic dehydration with a vacuum oven to simulate dehydration of the tissue beyond the epithelium.…”

Study of spatiotemporal liquid dynamics in a vibrating vocal fold by using a self-oscillating poroelastic model

“…It was commonly observed that mucus is usually aggregated on the superior edge in vocally normal speakers. 44 Moreover, by using a poroelastic model, Wu and Zhang 23 also found that an upward movement of water within the surface liquid layer along the medial surface results in a gradual water accumulation on the superior edge of the vocal fold. The phenomenon revealed by our model is consistent with clinical observations and other model predictions.…”

“…An interesting finding is that a global minimum in the total contact stress corresponds to physiologically reasonable tissue elasticity and fluid damping. Furthermore, Wu and Zhang 23 proposed a three-dimensional (3D) poroelastic model, considering water resupply, water movement within the tissue, water exchange through the epithelium, and surface fluid accumulation and discharge. They revealed that the dehydration generally increased with vibration amplitude, epithelial permeability, and reduced water resupply; moreover, the distribution of water loss within the vocal folds was non-uniform.…”

“…The poroelastic theory describes the dynamic behavior of the fluid component of vocal tissue and its interaction with the solid matrix. In comparison to the previous models, which did not consider the vocal fold contact, 18,19 ignored the solid-fluid interaction stress from the solid equations, 20,21 or imposed a time varying air pressure instead of a self-oscillating model, 23 this current model accounts for liquid-solid interaction, liquid movement, vocal fold contact, air pressure distribution obeying Bernoulli's law, and the flow-induced vocal fold self-vibration. Therefore, this model allows us to investigate the liquid movement in three directions and explores the effect of vocal fold contact on the liquid dynamics in vibrating vocal folds.…”

Voice perturbations under the stress overload in young individuals: phenotyping and suboptimal health as predictors for cascading pathologies

“…Dry mouth syndrome can result from some pathophysiological conditions, like exposure to acute and chronic stress, eating disorders (such as anorexia nervosa), metabolic syndrome(s), Sjögren's and Sicca syndromes, and head/neck radiotherapy application. In turn, hyposalivation may predispose individuals to chronic oral pain, dental caries, taste changes, halitosis, voice and digestive disorders, and burning mouth syndrome [11,98]. Xerostomia may impact tissue viscosity of the vocal tract and oral mucosa and subsequently influence vocal function [12].…”