scholarly journals The Role of Finite Displacements in Vocal Fold Modeling

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Siyuan Chang ◽  
Fang-Bao Tian ◽  
Haoxiang Luo ◽  
James F. Doyle ◽  
Bernard Rousseau
Keyword(s):  
Geometric Nonlinearity ◽  
Vocal Fold ◽  
Computational Models ◽  
Vocal Folds ◽  
Small Displacement ◽  
Linear Elasticity Theory ◽  
Finite Displacements ◽  
Medial Surfaces ◽  
Vocal Fold Dynamics ◽  
The Impact

Human vocal folds experience flow-induced vibrations during phonation. In previous computational models, the vocal fold dynamics has been treated with linear elasticity theory in which both the strain and the displacement of the tissue are assumed to be infinitesimal (referred to as model I). The effect of the nonlinear strain, or geometric nonlinearity, caused by finite displacements is yet not clear. In this work, a two-dimensional model is used to study the effect of geometric nonlinearity (referred to as model II) on the vocal fold and the airflow. The result shows that even though the deformation is under 1 mm, i.e., less than 10% of the size of the vocal fold, the geometric nonlinear effect is still significant. Specifically, model I underpredicts the gap width, the flow rate, and the impact stress on the medial surfaces as compared to model II. The study further shows that the differences are caused by the contact mechanics and, more importantly, the fluid-structure interaction that magnifies the error from the small-displacement assumption. The results suggest that using the large-displacement formulation in a computational model would be more appropriate for accurate simulations of the vocal fold dynamics.

Vocal Fold Dynamics During Phonations

2007 ◽  
Author(s):  
H. Lan ◽  
A. M. Al-Jumaily ◽  
A. Mirnajafi
Keyword(s):  
Finite Element ◽  
Risk Factor ◽  
Finite Element Model ◽  
Vocal Fold ◽  
Vocal Folds ◽  
Element Model ◽  
Glottal Closure ◽  
Vocal Fold Dynamics ◽  
The Impact ◽  
The Finite Element Model

During phonation, the vocal folds collision in the glottal closure is considered as a risk factor for pathology development. Based on the finite element model using the software ABAQUS™, the impact stresses between the vocal folds are studied.

scholarly journals Subglottal pressure oscillations in anechoic and resonant conditions and their influence on excised larynx phonations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hugo Lehoux ◽  
Vít Hampala ◽  
Jan G. Švec
Keyword(s):  
Vocal Fold ◽  
Computational Models ◽  
Vocal Folds ◽  
Voice Source ◽  
Resonance Frequencies ◽  
Subglottal Pressure ◽  
Radiated Sound ◽  
Acoustic Resonances ◽  
The Impact ◽  
Excised Larynx

AbstractExcised larynges serve as natural models for studying behavior of the voice source. Acoustic resonances inside the air-supplying tubes below the larynx (i.e., subglottal space), however, interact with the vibratory behavior of the larynges and obscure their inherent vibration properties. Here, we explore a newly designed anechoic subglottal space which allows removing its acoustic resonances. We performed excised larynx experiments using both anechoic and resonant subglottal spaces in order to analyze and compare, for the very first time, the corresponding subglottal pressures, electroglottographic and radiated acoustic waveforms. In contrast to the resonant conditions, the anechoic subglottal pressure waveforms showed negligible oscillations during the vocal fold contact phase, as expected. When inverted, these waveforms closely matched the inverse filtered radiated sound waveforms. Subglottal resonances modified also the radiated sound pressures (Level 1 interactions). Furthermore, they changed the fundamental frequency (fo) of the vocal fold oscillations and offset phonation threshold pressures (Level 2 interactions), even for subglottal resonance frequencies 4–10 times higher than fo. The obtained data offer the basis for better understanding the inherent vibratory properties of the vocal folds, for studying the impact of structure-acoustic interactions on voice, and for validation of computational models of voice production.

Nonlinear Vocal Fold Dynamics in a Two-Mass Model of Speech Arising From Asymmetric Intraglottal Flow

2011 ◽  
Author(s):  
Byron D. Erath ◽  
Matías Zañartu ◽  
Sean D. Peterson ◽  
Michael W. Plesniak
Keyword(s):  
Vocal Fold ◽  
Vocal Tract ◽  
Vocal Folds ◽  
Attractive Alternative ◽  
Nonlinear Phenomena ◽  
Mass Model ◽  
Sustained Oscillations ◽  
Voiced Speech ◽  
Subglottal Pressure ◽  
Vocal Fold Dynamics

Voiced speech is initiated as air is expelled from the lungs and passes through the vocal tract inciting self-sustained oscillations of the vocal folds. While various approaches exist for investigating both normal and pathological speech, the relative inaccessibility of the vocal folds make multi-mass speech models an attractive alternative. Their behavior has been benchmarked with excised larynx experiments, and they have been used as analysis tools for both normal and disordered speech, including investigations of paralysis, vocal tremor, and breathiness. However, during pathological speech, vocal fold motion is often unstructured, resulting in chaotic motion and a wealth of nonlinear phenomena. Unfortunately, current methodologies for multi-mass speech models are unable to replicate the nonlinear vocal fold behavior that often occurs in physiological diseased voice for realistic values of subglottal pressure.

Empirical Eigenfunctions and Medial Surface Dynamics of a Human Vocal Fold

2005 ◽  
Vol 44 (03) ◽  
pp. 384-391 ◽  
Author(s):  
N. Tayama ◽  
D. A. Berry ◽  
M. Döllinger
Keyword(s):  
Vocal Fold ◽  
High Speed ◽  
Computational Models ◽  
Imaging System ◽  
Vocal Folds ◽  
Sustained Oscillation ◽  
Medial Surface ◽  
Physical Mechanisms ◽  
Vocal Fold Vibration ◽  
Modes Of Vibration

Summary Objectives: The purpose of this investigation was to use an excised human larynx to substantiate physical mechanisms of sustained vocal fold oscillation over a variety of phonatory conditions. During sustained, flow-induced oscillation, dynamical data was collected from the medial surface of the vocal fold. The method of Empirical Eigenfunctions was used to analyze the data and to probe physical mechanisms of sustained oscillation. Methods: Thirty microsutures were mounted on the medial margin of a human vocal fold. Across five distinct phonatory conditions, the vocal fold was set into oscillation and imaged with a high-speed digital imaging system. The position coordinates of the sutures were extracted from the images and converted into physical coordinates. Empirical Eigenfunctions were computed from the time-varying physical coordinates, and mechanisms of sustained oscillation were explored. Results: Using the method of Empirical Eigenfunctions, physical mechanisms of sustained vocal fold oscillation were substantiated. In particular, the essential dynamics of vocal fold vibration were captured by two dominant Empirical Eigenfunctions. The largest Eigenfunction primarily captured the alternating convergent/ divergent shape of the medial surface of the vocal fold, while the second largest Eigenfunction primarily captured the lateral vibrations of the vocal fold. Conclusions: The hemi-larynx setup yielded a view of the medial surface of the vocal folds, revealing the tissue vibrations which produced sound. Through the use of Empirical Eigenfunctions, the underlying modes of vibration were computed, disclosing physical mechanisms of sustained vocal fold oscillation. The investigation substantiated previous theoretical analyses and yielded significant data to help evaluate and refine computational models of vocal fold vibration.

A Study of Vocal Fold Vibration Using a Slightly Compressible Fluid Domain

2009 ◽  
Author(s):  
D. J. Daily ◽  
S. L. Thomson
Keyword(s):  
Boundary Conditions ◽  
Incompressible Fluid ◽  
Compressible Fluid ◽  
Vocal Fold ◽  
Computational Models ◽  
Fluid Model ◽  
Vocal Folds ◽  
Moving Wall ◽  
Slightly Compressible ◽  
Vocal Fold Vibration

During human voice production, air forced from the lungs through the larynx induces vibration of the vocal folds. Computational models of this coupled fluid-solid system have traditionally utilized an incompressible fluid domain. However, studies have shown that coupling of tracheal acoustics with vocal fold dynamics is significant. Further, in the absence of compressibility, some models fail to achieve self-sustained vibration. This presentation discusses a slightly compressible airflow model, fully coupled with a vocal fold tissue model, as a possible substitute for the traditional incompressible approach. The derivation and justification of the slightly compressible fluid model are discussed. Results are reported of a study of the nature of the coupling between the fluid and vocal fold regions for both slightly compressible and incompressible fluid domains using a commercial fluid-solid finite element package. Three different types of inlet boundary conditions, including constant pressure, constant velocity, and moving wall, are explored. The incompressible and slightly compressible models with the three boundary conditions are compared with each other and with experimental data obtained using synthetic self-oscillating vocal fold models. The results are used to validate the slightly compressible flow model as well as to explore candidate boundary conditions for vocal fold vibration simulations.

S192 – 3D Diagnosis of Vocalizing Larynx Using Cone Beam CT

2008 ◽  
Vol 139 (2_suppl) ◽  
pp. P140-P140
Author(s):  
Koji Inagaki ◽  
Koichiro Saito ◽  
Hideki Naganishi ◽  
Takaoka Takuj ◽  
Momoshima Suketaka ◽  
...  
Keyword(s):  
Vocal Fold ◽  
3D Visualization ◽  
Cone Beam Ct ◽  
Vocal Folds ◽  
Cone Beam ◽  
3 Dimensional ◽  
Scanning Time ◽  
Informative Role ◽  
Glottal Insufficiency ◽  
The Impact

Objectives Cone beam computed tomography (CBCT) was developed for the office-based quick and precise 3D visualization of maxillofacial region. CBCT requires scanning time of less than 10 seconds and provides isotropic 3D image with high resolution. In this study, we examined the potential role of CBCT as a tool for 3-dimensional evaluation of the glottal insufficiency. Methods CBCT was performed in 2 normal controls and in 14 patients with unilateral vocal fold paralysis (13 cases) or paresis (1 case). Laryngeal CBCT images were taken in the resting state and during phonation. Furthermore, preoperative and postoperative images were evaluated to assess the impact of phonosurgeries in 5 cases. Results CBCT of the vocalizing vocal fold was successfully performed in all the cases, producing clear coronal images. During phonation, no remarkable differences in levels between the paralyzed and normal vocal folds were observed in 10 cases, proving the 2-dimensional glottal gap (2D cases). On the other hand, the levels of paralyzed vocal folds stayed higher during phonation compared to the normal side in 4 cases, proving the 3-dimensional glottal gap (3D cases). 4 of the 2D cases had injection laryngoplasty and 1 of the 3D cases had arytenoid adduction procedure to correct their glottal gaps. Postoperative CBCT images verified the successful correction of these gaps. Conclusions Our study proved the feasibility of CBCT for 3D evaluation of vocalizing larynx. This quick and easy system may have an informative role to suggest the proper phonosurgical procedure for glottic insufficiency.

scholarly journals Antioxidant Properties of Tonsil-Derived Mesenchymal Stem Cells on Human Vocal Fold Fibroblast Exposed to Oxidative Stress

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Sung-Chan Shin ◽  
Hyung-Sik Kim ◽  
Yoojin Seo ◽  
Cho Hee Kim ◽  
Ji Min Kim ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Cell Viability ◽  
Vocal Fold ◽  
Vocal Folds ◽  
Dependent Manner ◽  
The Impact

The therapeutic potential of tonsil-derived mesenchymal stem cells (TMSCs) has been proved in several in vitro and in vivo models based on their antioxidative capacity. Oxidative stress is involved in the formation of vocal fold scars and the aging of vocal folds. However, few studies have examined the direct correlation between oxidative damage and reconstitution of extracellular matrix (ECM) in the vocal fold fibrosis. We, therefore, sought to investigate the impact of oxidative stress on cell survival and ECM production of human vocal fibroblasts (hVFFs) and the protective effects elicited by TMSCs against oxidative damages in hVFFs. hVFFs were exposed to different concentrations of tert-butyl hydroperoxide in the presence or absence of TMSCs. Cell viability and reactive oxygen species (ROS) production were assessed to examine the progression of oxidative stress in vitro. In addition, expression patterns of ECM-associated factors including various collagens were examined by real-time PCR and immunocytochemical analysis. We found that both cell viability and proliferation capacity of hVFFs were decreased following the exposure to tBHP in a dose-dependent manner. Furthermore, tBHP treatment induced the generation of ROS and reactive aldehydes, while it decreased endogenous activity of antioxidant enzymes in hVFF. Importantly, TMSCs could rescue these oxidative stress-associated damages of hVFFs. TMSCs also downregulated tBHP-mediated production of proinflammatory cytokines in hVFFs. In addition, coculture with TMSC could restore the endogenous matrix metalloproteinase (MMP) activity of hVFFs upon tBHP treatment and, in turn, reduce the oxidative stress-induced ECM accumulation in hVFFs. We have, therefore, shown that the changes in hVFF proliferative capacity and ECM gene expression induced by oxidative stress are consistent with in vivo phenotypes observed in aging vocal folds and vocal fold scarring and that TMSCs may function to reduce oxidative stress in aging vocal folds.

A Wave Reflection Analog Extension for Reduced Order Vocal Fold Investigations With Asymmetric Intraglottal Flows

2012 ◽  
Author(s):  
Byron D. Erath ◽  
Sean D. Peterson ◽  
Matias Zañartu ◽  
Michael W. Plesniak
Keyword(s):  
Vocal Fold ◽  
Vocal Tract ◽  
Coupling Effect ◽  
Vocal Folds ◽  
Tissue Properties ◽  
Sustained Oscillations ◽  
Voiced Speech ◽  
Vocal Fold Dynamics ◽  
Static Fluid ◽  
Speech Science

Voiced speech involves complex fluid-structure-acoustic interactions. When a critical lung pressure is achieved, the vocal folds are pushed apart inciting self-sustained oscillations. The interplay between the aerodynamic forces and the myoelastic tissue properties produces robust oscillation of the vocal folds. The pulsatile nature of the flow as it emanates from vocal folds creates an oscillatory pressure field which acoustically excites the vocal tract and ultimately forms intelligible sound. Recently, it has been shown that the acoustic pressures are high enough in magnitude that they modulate the static fluid pressures which drive the flow.1 This coupling effect creates a feedback loop with the fluids, acoustics, and vocal fold dynamics becoming interconnected. Consequently, speech science investigations that aim to capture the relevant physics must consider all three components to yield credible, clinically-relevant results.

scholarly journals Subject-Specific Computational Modeling of Evoked Rabbit Phonation

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Siyuan Chang ◽  
Carolyn K. Novaleski ◽  
Tsuyoshi Kojima ◽  
Masanobu Mizuta ◽  
Haoxiang Luo ◽  
...  
Keyword(s):  
Vocal Fold ◽  
Computational Models ◽  
Three Dimensional ◽  
Model Parameters ◽  
Individual Subject ◽  
Vocal Fold Vibration ◽  
Subject Specific ◽  
Vocal Fold Dynamics ◽  
1D Model

When developing high-fidelity computational model of vocal fold vibration for voice production of individuals, one would run into typical issues of unknown model parameters and model validation of individual-specific characteristics of phonation. In the current study, the evoked rabbit phonation is adopted to explore some of these issues. In particular, the mechanical properties of the rabbit's vocal fold tissue are unknown for individual subjects. In the model, we couple a 3D vocal fold model that is based on the magnetic resonance (MR) scan of the rabbit larynx and a simple one-dimensional (1D) model for the glottal airflow to perform fast simulations of the vocal fold dynamics. This hybrid three-dimensional (3D)/1D model is then used along with the experimental measurement of each individual subject for determination of the vocal fold properties. The vibration frequency and deformation amplitude from the final model are matched reasonably well for individual subjects. The modeling and validation approaches adopted here could be useful for future development of subject-specific computational models of vocal fold vibration.

scholarly journals Evaluation of the impact of compliance of precast discs of overlapping on the work of the frame of a multi-storey building

2019 ◽  
Vol 97 ◽  
pp. 04022
Author(s):  
Nikolay Trekin ◽  
Emil Kodysh ◽  
Alexander Bybka ◽  
Alexander Yamalov ◽  
Nikita Konkov
Keyword(s):  
Economic Performance ◽  
Computational Models ◽  
Precast Concrete ◽  
Building Frames ◽  
Frame Building ◽  
Numerical Studies ◽  
Frame Buildings ◽  
The Impact ◽  
Structural Solutions ◽  
Storey Building

The article provides an analysis and justification of the need to take into account the compliance of discs of overlapping and coatings when calculating frames from precast concrete structures. Previously conducted full-scale experiments showed that the rigidity of the precast overlapping with full filling of the seams, in comparison with the monolithic overlapping, decreases by 3-15 times due to the ductility of the joints. The use of refined computational models of structural solutions for frames, which take into account the compliance of the conjugations of elements, makes it possible to trace possible redistribution of efforts. Such an approach when reconstructing, it is possible to optimally select and calculate the enforcement of structure, and on new designing, to increase reliability and / or improve the economic performance of frame buildings. According to the results of analytical studies, formulas were adopted for the parameters that allow one to take into account the overall compliance of overlapping disks and coatings in computational models of building frames. Numerical studies on the computational model of a frame building made it possible to evaluate the effect of accounting for compliance on the stress-strain state of a multi-storey frame.

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