## 3 Sensitivity of the Intraglottal and Vocal Fold Contact Pressures to Sensor Position
### Results
#### 3.2.2 Validation of Intraglottal and Vocal Fold Contact Pressure Measurements  
Intraglottal pressure waveforms were acquired in the synthetic VF model with a cover layer of \(E_{c}=0.95\) kPa, driven at a mean subglottal pressure of \(p_{\text{sub}}=2.00\) kPa. The mean flow rate was \(Q=376\) mL/s and the fundamental frequncy was \(f_{o}=138\) Hz. The medial prephonatory compression was set to MPC = 0.75 mm, which corresponds to a medial prephonatory pressure of MPP = 1.45 kPa. Following the procedure outlined in Section 3.1.4, the inferior-superior length of contact was measured to be 2.82 mm. Note, this is longer than the size of the window opening on the moveable contact plate (1.3 mm) in which the intraglottal pressure transducer was embedded. As such, when the intraglottal pressure transducer was placed at the midpoint of the contact location, the surface of the VF completely covered it during collision.  
Figure 14 presents the intraglottal pressure waveform at the midpoint of contact, averaged over 100 cycles. Comparing the synchronized HSV with the intraglottal pressure measurements identifies that the first peak in the waveform corresponds to the maximum VF contact pressure, denoted as \(p_{\text{cont}}\) in Figure 14. The peak contact pressure is followed by a drop in pressure because of the equalization of internal stresses in the VF while the pressure sensor is still totally covered by the contact area. Progression of the mucosal wave results in the inferior edge of the VF surface lifting, and exposing the inferior edge of the transducer to the subglottal pressure while there is still complete closure. This produces the subsequent rise in the pressure, and the second peak. As the VF fully opens, the flow accelerates through the glottal opening, and the pressure decreases. This double peak pattern is analogous to the intraglottal pressure waveform acquired with canine VFs at the same subglottal pressure [11], as shown in Figure 1. In both cases, the measured contact pressure is higher than the mean subglottal pressure. The average contact pressure for the synthetic VF model, averaged over 100 cycles, is 2.29 kPa, which is 15% greater than the subglottal pressure. Prior excised experiments [11] reported a peak contact pressure of \(\sim\)3 kPa with a subglottal pressure of 1.96 kPa. Nevertheless, very good agreement in the contact mechanics measured by the pressure sensor is observed. The difference in the ratio of \(p_{\text{cont}}/p_{\text{sub}}\) between these two models may arise because of the different geometry and tissue properties of the excised VF and also variations in the medial prephonatory pressure, which was not specified for the canine investigations. In addition, the excised canine experiments [11] positioned the pressure transducer such that it protruded above the contacting wall by \(\sim\)0.5 mm, and physical protrusion of the sensor has been shown to overestimate the contact pressure (see Section 2.3.1).  
Figure 13: Kymogram plot from the HSV with the location of the superior (\(--\)) and inferior (\(-\)) VF edge identified.