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Figure 6. Mid-coronal velocity flow fields of human (left column), canine (middle column), and synthetic (right column) vocal fold models at the MFDR. (a) Low Psg. (b) High Psg. (c) Axial velocity profiles extracted along the superior edge (white horizontal line). the folds. Although the magnitude of this angle increased with the increasing Psg in all models, its values were much greater in the tissue models.

Figure 6 Mid-coronal velocity flow fields of human (left column), canine (middle column), and synthetic (right column) vocal fold models at the MFDR. (a) Low Psg. (b) High Psg. (c) Axial velocity profiles extracted along the superior edge (white horizontal line). the folds. Although the magnitude of this angle increased with the increasing Psg in all models, its values were much greater in the tissue models.

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Figure 1. Schematic of the experimental setup used to capture the intraglottal flow field and glottal wall geometry using particle image velocimetry (PIV). (a) Cadaveric human larynx, (b) excised canine larynx, and (c) synthetic larynx, all mounted on an aerodynamic nozzle. Figure 1. Schematic of the experimental setup used to capture the intraglottal flow field and glottal section, connected to the trachea, was 25 mm long, with an inlet diameter of 12.7 mm and an exit diameter o guidelines provid represen transduc ting the subglottal press er, with the reported va Kjaer, Neerum, Denmar he glottis where it did not inter f 17.0 mm. The settling chamber and nozzle were designed following the ed by Morel [33] and Mehta [34]. The static pressure inside the nozzle, ure (Psg), was measured using a Honeywell FPG pressure ues time-averaged. The airflow was humidified (Hudson RCL, ConchaTherm III) and regulated using a flow controller (Parker, MPC series), a flow meter (MicroMotion Inc, CMF02 regulator (ControlAir Inc, Type hane tubing (3/4 in. OD, 1/8 in. wall) connected the various instruments. Acoustic ments were captured using a 1/4-inch omnidirectional microphone (Type 4958, 5 Coriolis Flow Meter, Boulder, CO, USA), and a pressure 00 Precision Air Pressure Regulator, Amherst, NH, USA) k) placed approximately 30 cm laterally and superiorly to fere with the airflow.
Figure 1. Schematic of the experimental setup used to capture the intraglottal flow field and glottal wall geometry using particle image velocimetry (PIV). (a) Cadaveric human larynx, (b) excised canine larynx, and (c) synthetic larynx, all mounted on an aerodynamic nozzle. Figure 1. Schematic of the experimental setup used to capture the intraglottal flow field and glottal section, connected to the trachea, was 25 mm long, with an inlet diameter of 12.7 mm and an exit diameter o guidelines provid represen transduc ting the subglottal press er, with the reported va Kjaer, Neerum, Denmar he glottis where it did not inter f 17.0 mm. The settling chamber and nozzle were designed following the ed by Morel [33] and Mehta [34]. The static pressure inside the nozzle, ure (Psg), was measured using a Honeywell FPG pressure ues time-averaged. The airflow was humidified (Hudson RCL, ConchaTherm III) and regulated using a flow controller (Parker, MPC series), a flow meter (MicroMotion Inc, CMF02 regulator (ControlAir Inc, Type hane tubing (3/4 in. OD, 1/8 in. wall) connected the various instruments. Acoustic ments were captured using a 1/4-inch omnidirectional microphone (Type 4958, 5 Coriolis Flow Meter, Boulder, CO, USA), and a pressure 00 Precision Air Pressure Regulator, Amherst, NH, USA) k) placed approximately 30 cm laterally and superiorly to fere with the airflow.
Figure 2. Force-displacement measurements. (a) Cadaveric human vocal fold. (b) Excised canine vocal fold. The pink color is from the dye applied to minimize the reflections from tissue during PIV measurements (c) Synthetic vocal fold before (top) and after (bottom) applying paint. (d) Schematic of the experimental setup used to collect normal force—displacement measurements. Thee astic properties of the vocal folds for t o the procedure outlined by Dion et al. [36]. Fo he tissue models were bisected in the sagittal plane to create a hemilarynx configuration. A pecific ho der was molded from plaster material he three models were collected according lowing the aerodynamic measurements, for each larynx (Figure 2). The hemilarynx vas affixed to the model mold using cyanoacrylate adhesive. The tissues were kept moist efore and aster ho during the testing using a phosphate der was cast for the synthetic fold, bu he testing. buffered saline (PBS) solution. A similar the saline solution was not used during
Figure 2. Force-displacement measurements. (a) Cadaveric human vocal fold. (b) Excised canine vocal fold. The pink color is from the dye applied to minimize the reflections from tissue during PIV measurements (c) Synthetic vocal fold before (top) and after (bottom) applying paint. (d) Schematic of the experimental setup used to collect normal force—displacement measurements. Thee astic properties of the vocal folds for t o the procedure outlined by Dion et al. [36]. Fo he tissue models were bisected in the sagittal plane to create a hemilarynx configuration. A pecific ho der was molded from plaster material he three models were collected according lowing the aerodynamic measurements, for each larynx (Figure 2). The hemilarynx vas affixed to the model mold using cyanoacrylate adhesive. The tissues were kept moist efore and aster ho during the testing using a phosphate der was cast for the synthetic fold, bu he testing. buffered saline (PBS) solution. A similar the saline solution was not used during
Plotting the width of the glottal opening in the mid-coronal shows a comparison between the motion of the folds during vibration in each larynx model. This width was extracted at the superior aspect from the PIV images, and its value is assumed to be proportional to the glottal opening area. All models were characterized by opening, closing, and closed phases during their vibration cycle (Figure 3a). The resultant glottal width waveform was used to calculate the open quotient (OQ) and area skewness index (Slwigth) values (Figure 3b,c). Waveform examples for HL1, CL1, and SL1 are shown in Figure 3a.
Plotting the width of the glottal opening in the mid-coronal shows a comparison between the motion of the folds during vibration in each larynx model. This width was extracted at the superior aspect from the PIV images, and its value is assumed to be proportional to the glottal opening area. All models were characterized by opening, closing, and closed phases during their vibration cycle (Figure 3a). The resultant glottal width waveform was used to calculate the open quotient (OQ) and area skewness index (Slwigth) values (Figure 3b,c). Waveform examples for HL1, CL1, and SL1 are shown in Figure 3a.
Figure 3. Mid-coronal width analysis of human (left column), canine (middle column), and synthetic (right column) vocal fold models during phonation. (a) Glottal width waveform. (b) Open quotient. (c) Superior width skewness index [38-41].
Figure 3. Mid-coronal width analysis of human (left column), canine (middle column), and synthetic (right column) vocal fold models during phonation. (a) Glottal width waveform. (b) Open quotient. (c) Superior width skewness index [38-41].
Figure 4. Mid-coronal width trends of human, canine, and synthetic vocal fold models during phonation. (a) Open quotient. (b) Superior width skewness index. (c) Glottal divergence angle at the MFDR. In all cases, the OQ, SIwidth, and the divergence angle at the instant of the MFDR phase increased with Psg (Figure 4). The Slwiqe, values increased the most in the human (Figure 4b), while the canine and synthetic trends remained constant for both the OQ and Slwidth parameters. The glottal divergence angle, defined as the total angle between the folds at the MFDR phase, was extracted from the PIV measurements (shown in Section 3.2. Glottal Flow Characteristics). The magnitude of the divergence angle at the MFDR phase appeared to be similar in the tissue models and higher than in the synthetic models (Figure 4c).
Figure 4. Mid-coronal width trends of human, canine, and synthetic vocal fold models during phonation. (a) Open quotient. (b) Superior width skewness index. (c) Glottal divergence angle at the MFDR. In all cases, the OQ, SIwidth, and the divergence angle at the instant of the MFDR phase increased with Psg (Figure 4). The Slwiqe, values increased the most in the human (Figure 4b), while the canine and synthetic trends remained constant for both the OQ and Slwidth parameters. The glottal divergence angle, defined as the total angle between the folds at the MFDR phase, was extracted from the PIV measurements (shown in Section 3.2. Glottal Flow Characteristics). The magnitude of the divergence angle at the MFDR phase appeared to be similar in the tissue models and higher than in the synthetic models (Figure 4c).
Figure 5. Mid-coronal flow analysis of human (left column), canine (middle column), and synthetic (right column) vocal fold models during phonation. (a) Two-dimensional glottal flow waveform. (b) Flow skewness index. Plotting the two-dimensional flow rate (Q*) in the mid-coronal location compares the waveforms from each larynx model. The flow rate was calculated by integrating the axial velocity along the glottal exit (superior edge) at each phase, and examples of the resulting waveforms are shown for HL1, CL1, and SL1 in Figure 5a. Similar to the fold’s displacement, the peak Q* increased with the increasing Psg in all models, but the shift in Q* skewing was observed only in the tissue models. Furthermore, the value of the flow skewness index (Slow) in some of the synthetic models was less than one (SIfow < 1), signifying a prolonged closing phase (compared with opening), which was the opposite of the tissue models (Figure 5b).
Figure 5. Mid-coronal flow analysis of human (left column), canine (middle column), and synthetic (right column) vocal fold models during phonation. (a) Two-dimensional glottal flow waveform. (b) Flow skewness index. Plotting the two-dimensional flow rate (Q*) in the mid-coronal location compares the waveforms from each larynx model. The flow rate was calculated by integrating the axial velocity along the glottal exit (superior edge) at each phase, and examples of the resulting waveforms are shown for HL1, CL1, and SL1 in Figure 5a. Similar to the fold’s displacement, the peak Q* increased with the increasing Psg in all models, but the shift in Q* skewing was observed only in the tissue models. Furthermore, the value of the flow skewness index (Slow) in some of the synthetic models was less than one (SIfow < 1), signifying a prolonged closing phase (compared with opening), which was the opposite of the tissue models (Figure 5b).
Figure 7. Mid-coronal vorticity flow fields of human (left column), canine (middle column), and synthetic (right column) vocal fold models at the MFDR. (a) Low Psg. (b) High Psg. (c) Total circulation (within the outlined region).
Figure 7. Mid-coronal vorticity flow fields of human (left column), canine (middle column), and synthetic (right column) vocal fold models at the MFDR. (a) Low Psg. (b) High Psg. (c) Total circulation (within the outlined region).
Figure 8. Glottal flow and acoustic characteristics of human, canine, and synthetic vocal fold models. (9) Flow ckewnece index (h) |MBEBDRI! (c) Total circulation (d) VE. where R is the distance from the microphone to the sound source, SPL is the sound pressure level, Q is the mean glottal flow rate recorded from the upstream flow meter, and Psg is the mean subglottal pressure [43]. These parameters in the canine models are higher than in the human and synthetic models.
Figure 8. Glottal flow and acoustic characteristics of human, canine, and synthetic vocal fold models. (9) Flow ckewnece index (h) |MBEBDRI! (c) Total circulation (d) VE. where R is the distance from the microphone to the sound source, SPL is the sound pressure level, Q is the mean glottal flow rate recorded from the upstream flow meter, and Psg is the mean subglottal pressure [43]. These parameters in the canine models are higher than in the human and synthetic models.
Figure 9. Elasticity measurements along the vertical height of each model in the mid—coronal plane (HL1 [left column], CL1 [middle column], and SL1 [right column]). (a) Stress—strain curve. Vertical lines mark the location where the maximum displacement of the folds was observed at high and low Psg values. (b) Corresponding Young’s modulus values calculated at the maximum fold displacement [18—20,26].
Figure 9. Elasticity measurements along the vertical height of each model in the mid—coronal plane (HL1 [left column], CL1 [middle column], and SL1 [right column]). (a) Stress—strain curve. Vertical lines mark the location where the maximum displacement of the folds was observed at high and low Psg values. (b) Corresponding Young’s modulus values calculated at the maximum fold displacement [18—20,26].
Table 1. Summary of mean measured parameters and standard deviation for each vocal fold model. 4. Discussion
Table 1. Summary of mean measured parameters and standard deviation for each vocal fold model. 4. Discussion
Figure 10. VSG as a function of Psg (i.e., strain) for the human, canine, and synthetic vocal fold models The VSG as a function of Psg highlights the notable differences between the tissue and synthetic models (Figure 10). In tissue models, nonlinearity is evident as the VSG increases with strain, due to an increase in Psg. Conversely, in synthetic models, the VSG remains constant with increasing strain, also due to a rising Psg. This behavior occurs because the silicone synthetic model is primarily elastic and exhibits little to no hysteresis.
Figure 10. VSG as a function of Psg (i.e., strain) for the human, canine, and synthetic vocal fold models The VSG as a function of Psg highlights the notable differences between the tissue and synthetic models (Figure 10). In tissue models, nonlinearity is evident as the VSG increases with strain, due to an increase in Psg. Conversely, in synthetic models, the VSG remains constant with increasing strain, also due to a rising Psg. This behavior occurs because the silicone synthetic model is primarily elastic and exhibits little to no hysteresis.
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