## Materials and Methods
### Data Collection  
Following the clinical videostroboscopic assessment, the participant underwent a laryngeal high-speed videoendoscopic assessment with simultaneously recorded vocal function sensors. The endoscopist (a laryngologist who regularly performs outpatient transoral vocal fold injections) positioned the ISP probe with the left hand against the scar band on the right side of the larynx and synchronously recorded laryngeal high-speed videoendoscopy via a 70-degree transoral rigid endoscope (10 mm outer diameter; JEDMED, St. Louis, MO, USA) held in the right hand. The high-speed camera was attached to the eyepiece of the endoscope (FASTCAM Model MC2, Photron, Tokyo, Japan) using a 45 mm focal length lens adapter (PENTAX Medical, Montvale, NJ, USA) and high-speed videoendoscopy data were recorded with a Color High-Speed Video System (Model 9710, PENTAX Medical, Montvale, NJ, USA). The high-speed video data were recorded at 2000 frames per second with maximum frame integration time (\(\sim\)0.5 ms) and a spatial resolution of 512 pixels \(\times\) 512 pixels. The imaging light source consisted of a 300-watt short-arc xenon lamp. Five channels of sensor data recorded by an acoustic microphone, electroglottograph, neck-surface accelerometer, and the two pressure sensors of the ISP probe were time-synchronized with the high-speed video data. The acoustic signal was recorded 15 cm from the lips using a head-mounted, omnidirectional microphone (model ME102, Sennheiser Electronic GmbH, Wedemark-Wennebostel, Germany). Electroglottography (Model EG2-PC; Glottal Enterprises, Syracuse, NY, USA) provided a signal associated with vocal fold tissue contact that is high-pass filtered to reduce noise and low-frequency conductance changes. Neck-surface vibration was measured using an accelerometer (BU-27135; Knowles, Iasca, IL, USA) that can be analyzed to yield glottal airflow estimates [37; 38] and has shown potential for long-term monitoring of vocal function, e.g., [39; 40; 41; 42]. The accelerometer was enclosed in a silicone epoxy and mounted onto the participant's neck halfway between the sternal notch and thyroid prominence using Double Stick Discs (Model 2181, 3M, Maplewood, MN, USA). Figure 2 displays a photograph of the dual-sensor ISP probe and its dimensions [13]. The width of the probe tip was 4.4 mm, and the probe tip length (before curvature began) was 28 mm. The thickness of the probe at the sensor locations was maximally 1.9 mm, which is larger than in previous devices (0.4 mm [9; 10] and 0.29 mm [8]) due to the dimensions of the pressure-sensing elements. The effect of the thickness of the probe tip was mitigated by the placement of the probe against the surgically reconstructed vocal fold (scar band) of the study participant as the contralateral vocal fold came into contact with the pressure probe. The two probe catheters were connected, via extender adapter cables, to a two-channel signal conditioning unit (PCU-2000, Millar, Inc., Houston, TX, USA) that provides electrical isolation, analog knoks for zero control, and a flat frequency response of 0-1000 Hz. Measurement of intraglottal and subglottal pressures was accomplished using the two miniature, pressure-sensitive sensors of the ISP probe, respectively (Mikro-Cath Pressure Catheter, Millar, Inc., Houston, TX, USA). The pressure-sensing elements consisted of diffused, piezoresistive semiconductors with a dynamic range of \(-\)6.7 kPa to 40 kPa (\(-\)70 cm H\({}_{2}\)O to 400 cm H\({}_{2}\)O) and a flat frequency response up to 10 kHz. Each pressure transducer consists of an ovoid capsule that is 4.8 mm long and 1.17 mm in diameter, connected to a 120 cm long flexible cable. The sensing element measured 1.0 mm \(\times\) 1.0 mm (sensing area of 1.0 mm\({}^{2}\)) and was recessed 0.37 mm into the cylindrical surface of the transducer [12].