Modeling of the human larynx with application to the influence of false vocal folds on the glottal flow

2013 ◽  
Author(s):  
Mehrdad Hosnieh Farahani
Keyword(s):  
Vocal Folds ◽  
Human Larynx ◽  
Glottal Flow ◽  
False Vocal

Flow Visualization and Acoustic Consequences of the Air Moving Through a Static Model of the Human Larynx

2005 ◽  
Vol 128 (3) ◽  
pp. 380-390 ◽  
Author(s):  
Bogdan R. Kucinschi ◽  
Ronald C. Scherer ◽  
Kenneth J. DeWitt ◽  
Terry T. M. Ng
Keyword(s):  
Flow Visualization ◽  
Flow Structure ◽  
Flow Rate ◽  
Real Life ◽  
Vocal Folds ◽  
Jet Flow ◽  
Scale Model ◽  
Flow Structures ◽  
Human Larynx ◽  
False Vocal

Flow visualization with smoke particles illuminated by a laser sheet was used to obtain a qualitative description of the air flow structures through a dynamically similar 7.5× symmetric static scale model of the human larynx (divergence angle of 10deg, minimal diameter of 0.04cm real life). The acoustic level downstream of the vocal folds was measured by using a condenser microphone. False vocal folds (FVFs) were included. In general, the glottal flow was laminar and bistable. The glottal jet curvature increased with flow rate and decreased with the presence of the FVFs. The glottal exit flow for the lowest flow rate showed a curved jet which remained laminar for all geometries. For the higher flow rates, the jet flow patterns exiting the glottis showed a laminar jet core, transitioning to vortical structures, and leading spatially to turbulent dissipation. This structure was shortened and tightened with an increase in flow rate. The narrow FVF gap lengthened the flow structure and reduced jet curvature via acceleration of the flow. These results suggest that laryngeal flow resistance and the complex jet flow structure exiting the glottis are highly affected by flow rate and the presence of the false vocal folds. Acoustic consequences are discussed in terms of the quadrupole- and dipole-type sound sources due to ordered flow structures.

scholarly journals A Numerical and Experimental Investigation of the Effect of False Vocal Fold Geometry on Glottal Flow

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Mehrdad H. Farahani ◽  
John Mousel ◽  
Fariborz Alipour ◽  
Sarah Vigmostad
Keyword(s):  
Pressure Distribution ◽  
Vocal Fold ◽  
Pressure Fluctuations ◽  
Vocal Folds ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Pressure Data ◽  
Time Period ◽  
Glottal Flow ◽  
False Vocal

The false vocal folds are hypothesized to affect the laryngeal flow during phonation. This hypothesis is tested both computationally and experimentally using rigid models of the human larynges. The computations are performed using an incompressible Navier–Stokes solver with a second order, sharp, immersed-boundary formulation, while the experiments are carried out in a wind tunnel with physiologic speeds and dimensions. The computational flow structures are compared with available glottal flow visualizations and are employed to study the vortex dynamics of the glottal flow. Furthermore, pressure data are collected on the surface of the laryngeal models experimentally and computationally. The investigation focuses on three geometric features: the size of the false vocal fold gap; the height between the true and false vocal folds; and the width of the laryngeal ventricle. It is shown that the false vocal fold gap has a significant effect on glottal flow aerodynamics, whereas the second and the third geometric parameters are of lesser importance. The link between pressure distribution on the surface of the larynx and false vocal fold geometry is discussed in the context of vortex evolution in the supraglottal region. It was found that the formation of the starting vortex considerably affects the pressure distribution on the surface of the larynx. The interaction of this vortex structure with false vocal folds creates rebound vortices in the laryngeal ventricle. In the cases of small false vocal fold gap, these rebound vortices are able to reach the true vocal folds during a time period comparable with one cycle of the phonation. Moreover, they can create complex vorticity patterns, which result in significant pressure fluctuations on the surface of the larynx.

A Study on the Effect of False Vocal Folds Gap Size on the Self-Sustained Oscillation of True Vocal Folds

2013 ◽  
Author(s):  
Mehrdad H. Farahani ◽  
John Mousel ◽  
Sarah Vigmostad
Keyword(s):  
Vocal Folds ◽  
The Self ◽  
Sustained Oscillation ◽  
Mean Values ◽  
Wide Range ◽  
Human Larynx ◽  
Normal Configuration ◽  
False Vocal ◽  
Ventricular Folds ◽  
Different Levels

Recent studies have shown that the supraglottic structures could alter the aeroacoustics output of the larynx [1–2]. The fist supraglottic tissue above the true vocal folds (TVF) is the false vocal folds (FVF) or ventricular folds. This non-oscillatory part of the human larynx shows a wide range of adductions during the normal phonation. Most previous studies, however, have focused on the effect of normal configuration of the FVFs based on mean values reported for this laryngeal structure. Therefore, the effect of different levels of FVF adduction on oscillation of the TVFs remained uninvestigated.

scholarly journals Computational study of false vocal folds effects on unsteady airflows through static models of the human larynx

2015 ◽  
Vol 48 (7) ◽  
pp. 1248-1257 ◽  
Author(s):  
Charles Farbos de Luzan ◽  
Jie Chen ◽  
Mihai Mihaescu ◽  
Sid M. Khosla ◽  
Ephraim Gutmark
Keyword(s):  
Computational Study ◽  
Vocal Folds ◽  
Human Larynx ◽  
Static Models ◽  
False Vocal

Spontaneous perforation of cervical oesophagus: a rare variant of Boerhaave's syndrome

2009 ◽  
Vol 123 (12) ◽  
pp. 1378-1380 ◽  
Author(s):  
S Mittal ◽  
A Rohatgi ◽  
R P Sutcliffe ◽  
A Botha
Keyword(s):  
Vocal Folds ◽  
Sudden Onset ◽  
Water Soluble ◽  
Uneventful Recovery ◽  
Oesophageal Perforation ◽  
Nasogastric Feeding ◽  
Computed Tomography Scanning ◽  
Difficulty Breathing ◽  
The Right ◽  
False Vocal

AbstractBackground:A 29-year-old man presented with sudden onset of severe pain in his throat, difficulty breathing and a hoarse voice, following an episode of vomiting.Investigations:Initial laboratory tests were normal. The patient underwent fibre-optic nasendoscopy, which demonstrated a haematoma in the piriform fossa. Lateral neck radiography and subsequent computed tomography scanning confirmed a 2 cm, loculated, gas-containing collection at the level of the vallecula in the right posterolateral wall, extending to the false vocal folds and communicating between the right parapharyngeal space and the right carotid sheath. Water-soluble contrast swallow confirmed the diagnosis.Diagnosis:Contained oesophageal perforation.Management:Conservative treatment was adopted involving nil orally, intravenous antibiotics and nasogastric feeding. The patient made an uneventful recovery.

A Comparison of Laser-Protected Endotracheal Tubes

2018 ◽  
Vol 159 (5) ◽  
pp. 871-878
Author(s):  
James A. Burns ◽  
Stephen D. Adlard ◽  
James B. Kobler ◽  
Monica A. Tynan ◽  
Robert H. Petrillo ◽  
...  
Keyword(s):  
Vocal Folds ◽  
Physical Characteristics ◽  
Airway Protection ◽  
Average Force ◽  
Endotracheal Tubes ◽  
Human Larynx ◽  
Endoscopic Laser ◽  
Resultant Increase ◽  
Academic Laboratory ◽  
Endoscopic Laser Surgery

Objectives To compare the physical characteristics of 3 laser-protected endotracheal tubes (LPETs) commonly used in endoscopic laser surgery. To report potential intraoperative problems related to LPET use and suggest practical solutions. Study Design Comparative analysis. Setting Academic laboratory. Subjects and Methods Physical characteristics of the Mallinckrodt Laser-Flex (MTL), Medtronic Laser-Shield II (ML-II), and Rusch LaserTubus (RL) were compared. The effect of bending LPETs on airflow resistance was estimated with a pressure transducer. The force required to pull each tube through the glottis and the pressure exerted during this maneuver were measured in a fresh cadaveric human larynx. Results The design features and physical characteristics of LPETs differ, including varying balloon-tip lengths. Bending LPETs to acute angles caused significant pressure increase within the RL tube (Δ 3.42 cm H2O) and minimal change within the ML-II (Δ 0.12 cm H2O) and MTL (Δ 0.21 cm H2O) tubes. The average force required to pull the RL (48.12 g, P = .003) and MTL (282.4 g, P = .001) tubes through the glottis was 7.6× and 44.5× greater than that for the ML-II (6.39 g). When pulled through the vocal folds, the ML-II cuff exerted no detectable pressure, whereas higher pressures were measured for the RL (2.2 cm H2O) and MTL (6.5 cm H2O) tubes. Conclusion The ML-II tube had the most favorable characteristics, with minimal pressure during extubation and resistance to kinking. The RL tube kinks readily with a resultant increase in resistance to airflow. The MTL tube extends farther into the trachea due to a relatively elongated balloon-tip configuration. Future LPET designs should incorporate features that avoid intraoperative difficulties related to airway protection and ventilation.

Determination of Mechanical Stresses in Vibration and Contact During Flow-Structure-Interaction in Vocal Folds

2011 ◽  
Author(s):  
Pinaki Bhattacharya ◽  
Thomas H. Siegmund
Keyword(s):  
Surface Deformation ◽  
Three Dimensional ◽  
Vocal Folds ◽  
Biomechanical Properties ◽  
Mechanical Stresses ◽  
Physical Models ◽  
Tissue Properties ◽  
Transient Nature ◽  
Superior Surface ◽  
Glottal Flow

Mechanical stresses in vocal folds (VFs) developed during self-oscillation — due to interaction with the glottal flow — play an important role in tissue damage and healing. Contact stresses occurring due to collision between VFs modify both self-oscillation characteristics, as well as stresses. The complexity of the problem is increased due to other factors acting in combination: transient nature of the flow, non-linear and anisotropic biomechanical properties of the VFs, and acoustic loading. Experiments with physical models [1] have attempted to deduce the state of stress in the interior through measurement of superior surface deformation. However, these methods pose challenges in data acquisition. on the other hand, full three-dimensional transient computational analysis of a self-oscillating and contacting VF model requires highly sophisticated algorithms as well as prohibitive resource usage. Not surprisingly, therefore, it has not been conducted until now. We hypothesize that a high-fidelity numerical simulation incorporating realistic tissue properties is essential to accurately determine stresses within VFs during self-oscillation and contact.

Design of Apparatus for Studying Aerodynamics of Voice Production

2004 ◽  
Author(s):  
Michael Barry
Keyword(s):  
Flow Visualization ◽  
Vocal Fold ◽  
Sound Production ◽  
Vocal Tract ◽  
Vocal Folds ◽  
Flow Speed ◽  
Working Fluid ◽  
Voice Production ◽  
Experimental Apparatus ◽  
Glottal Flow

The design and testing of an experimental apparatus for in vitro study of phonatory aerodynamics (voice production) in humans is presented. The presentation includes not only the details of apparatus design, but flow visualization and Digital Particle Image Velocimetry (DPIV) measurements of the developing flow that occurs during the opening of the constriction from complete closure. The main features of the phonation process have long been understood. A proper combination of air flow from the lungs and of vocal fold tension initiates a vibration of the vocal folds, which in turn valves the airflow. The resulting periodic acceleration of the airstream through the glottis excites the acoustic modes of the vocal tract. It is further understood that the pressure gradient driving glottal flow is related to flow separation on the downstream side of the vocal folds. However, the details of this process and how it may contribute to effects such as aperiodicity of the voice and energy losses in voiced sound production are still not fully grasped. The experimental apparatus described in this paper is designed to address these issues. The apparatus itself consists of a scaled-up duct in which water flows through a constriction whose width is modulated by motion of the duct wall in a manner mimicking vocal fold vibration. Scaling the duct up 10 times and using water as the working fluid allows temporally and spatially resolved measurements of the dynamically similar flow velocity field using DPIV at video standard framing rates (15Hz). Dynamic similarity is ensured by matching the Reynolds number (based on glottal flow speed and glottis width) of 8000, and by varying the Strouhal number (based on vocal fold length, glottal flow speed, and a time scale characterizing the motion of the vocal folds) ranging from 0.01 to 0.1. The walls of the 28 cm × 28 cm test section and the vocal fold pieces are made of clear cast acrylic to allow optical access. The vocal fold pieces are 12.7 cm × 14 cm × 28 cm and are rectangular in shape, except for the surfaces which form the glottis, which are 6.35 cm radius half-circles. Dye injection slots are placed on the upstream side of both vocal field pieces to allow flow visualization. Prescribed motion of the vocal folds is provided by two linear stages. Linear bearings ensure smooth execution of the motion prescribed using a computer interface. Measurements described here use the Laser-Induced Fluorescence (LIF) flow visualization and DPIV techniques and are performed for two Strouhal numbers to assess the effect of opening time on the development of the glottal jet. These measurements are conducted on a plane oriented perpendicular to the glottis, at the duct midplane. LIF measurements use a 5W Argon ion laser to produce a light sheet, which illuminates the dye injected through a slot in each vocal fold piece. Two dye colors are used, one for each side. Quantitative information about the velocity and vorticity fields are obtained through DPIV measurements at the same location as the LIF measurements.

The effects of the false vocal folds on laryngeal pressures and flows

2006 ◽  
Vol 120 (5) ◽  
pp. 3354-3354
Author(s):  
Li Sheng ◽  
Ronald C. Scherer ◽  
Wan MingXi ◽  
Wang SuPin ◽  
Qi LiYun
Keyword(s):  
Vocal Folds ◽  
False Vocal
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