Infraglottal Medialization: Increasing Vocal Fold Stiffness Gradient for Improved Vocal Efficiency.

Objectives/hypothesis: Assess the impact of the infraglottal medialization technique on acoustics and the vertical stiffness gradient of the vocal fold using excised canine larynges.

Methods: Seven ex vivo canine larynges were tested in three states: 1) no implant, 2) medialized using a glottal implant, and 3) medialized fold using an infraglottal implant. Outcome measures were vocal efficiency and stiffness of the fold.

Comparison of Aerodynamic and Elastic Properties in Tissue and Synthetic Models of Vocal Fold Vibrations.

Three laryngeal models were used to investigate the aerodynamic and elastic properties of vocal fold vibration: cadaveric human, excised canine, and synthetic silicone vocal folds. The aim was to compare the characteristics of these models to enhance our understanding of phonatory mechanisms. Flow and medial glottal wall geometry were acquired via particle image velocimetry.

Acoustics and aerodynamic effects following glottal and infraglottal medialization in an excised larynx model.

Objective: This study aimed to investigate the impact of the implant's vertical location during Type 1 Thyroplasty (T1T) on acoustics and glottal aerodynamics using excised canine larynx model, providing insights into the optimal technique for treating unilateral vocal fold paralysis (UVFP).

Methods: Measurements were conducted in six excised canine larynges using Silastic implants. Two implant locations, glottal and infraglottal, were tested for each larynx at low and high subglottal pressure levels.

The Effect of an Increasing Subglottal Stenosis Constriction That Extends From the Vocal Folds to the Inferior Border of the Cricoid Cartilage.

Acquired subglottal stenosis is an unpredicted complication that can occur in some patients who have undergone prolonged endotracheal intubation. It is a narrowing of the airway at the level of the cricoid cartilage that can restrict airflow and cause breathing difficulty. Stenosis is typically treated with endoscopic airway dilation, with some patients experiencing multiple recurrences.

Acoustic Screening of the "Wet voice": Proof of Concept in an ex vivo Canine Laryngeal Model.

Background: Current protocols for bedside swallow evaluation have high rates of false negative results. Though experts are not consistently able to screen for aspiration risk by assessing vocal quality, there is emerging evidence that vocal acoustic parameters are significantly different in patients at risk of aspiration. Herein, we aimed to determine whether the presence of material on the vocal folds in an excised canine laryngeal model may have an impact on acoustic and aerodynamic measures.

Fluid-Structure Interaction Analysis of Aerodynamic and Elasticity Forces During Vocal Fold Vibration.

The effect of the intraglottal vortices on the glottal flow waveform was explored using flow-structure-interaction (FSI) modeling. These vortices form near the superior aspect of the vocal folds during the closing phase of the folds' vibration. The geometry of the vocal fold was based on the well-known M5 model.

An Ex-vivo Model Examining Acoustics and Aerodynamic Effects Following Medialization With and Without Arytenoid Adduction.

Objectives/hypothesis: Quantify differences in acoustics and intraglottal flow fields between Thyroplasty Type 1 (TT1) with and without arytenoid adduction (AA) using excised canine larynx model.

Study Design: Basic science experiments using excised larynges.

Methods: Surgical procedures were implemented in eight excised canine larynges.

Computational Modeling of Voice Production Using Excised Canine Larynx.

A combined experimental-numerical work was conducted to comprehensively validate a subject-specific continuum model of voice production in larynx using excised canine laryngeal experiments. The computational model is a coupling of the Navier-Stokes equations for glottal flow dynamics and a finite element model of vocal fold dynamics. The numerical simulations employed a cover-body vocal fold structure with the geometry reconstructed from magnetic resonance imaging scans and the material properties determined through an optimization-based inverse process of experimental indentation measurement.

Volume velocity in a canine larynx model using time‑resolved tomographic particle image velocimetry.

In the classic source-filter theory, the source of sound is flow modulation. "Flow" is the flow rate () and flow modulation is d/d. Other investigators have argued, using theoretical, computational, and mechanical models of the larynx, that there are additional sources of sound.

Impact of Vertical Stiffness Gradient on the Maximum Divergence Angle.

Introduction: During vocal fold vibration, the medial surface of both folds forms a convergent shape during opening and a divergent shape during closing. A greater maximum divergence angle is associated with greater closing forces which will increase the closing speed of the glottis. An increased closing speed results in a greater acoustic intensity and greater vocal efficiency.

Quantification of the Intraglottal Pressure Induced by Flow Separation Vortices Using Large Eddy Simulation.

The greatest rate of change in the glottal flow rate during phonation is a rapid decrease that occurs during the latter part of the glottal closing. Previous works showed that intraglottal flow separation vortices form in a divergent glottis, produce negative gauge pressures (below atmospheric) during closing. It is hypothesized here that flow separation vortices contribute to the rapid closing mechanism of the true vocal folds during phonation.

Effects of False Vocal Folds on Intraglottal Velocity Fields.

Previous models have theorized that, during phonation, skewing of the glottal waveform (which is correlated with acoustic intensity) occurred because of inertance of the vocal tract. Later, we reported that skewing of the flow rate waveform can occur without the presence of a vocal tract in an excised canine larynx. We hypothesized that in the absence of a vocal tract, the skewing formed when dynamic pressures acted on the glottal wall during the closing phase; such pressures were greatly affected by formation of intraglottal vortices.

Endoscopic posterior cricoid reduction: A surgical method to improve posterior glottic diastasis.

Objectives/hypothesis: Describe the preoperative evaluation of patients with glottic diastasis who are candidates for endoscopic posterior cricoid reduction (EPCR) and their perioperative and postoperative surgical and voice outcomes, and validate the aerodynamic benefit of EPCR using computation fluid dynamics (CFD)-based modeling from computed tomography (CT) scans.

Study Design: Retrospective case series.

Methods: Thirteen patients who underwent EPCR were followed from 2013 to 2017.

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

Compressible large eddy simulation is employed to numerically investigate the laryngeal flow. Symmetric static models of the human larynx with a divergent glottis are considered, with the presence of false vocal folds (FVFs). The compressible study agrees well with that of the incompressible study.