## 2 Materials and Methods  
The data acquisition was already previously described in detail [39]; hence the following is only a short overview of the experimental setup and data collection. For detailed information, we refer to the reference study on type 1 oscillations [39]. Data from 11 ex vivo rabbit larynes (New Zealand White, 4-5 kg body weight, ages 14-118 weeks) were used for this study. Since the rabbits were already sacrificed for another study with buprenorphine, no further approval of the ethics committee was required. Ethical acceptability was approved for the previous study (approval number 54-2532.1-54/12). In preparation for the experiments, the larynes were harvested from the sacrificed rabbits. Then the tissue just above and 30 mm below the larynes was surgically removed. To preserve the tissue characteristics, the prepared larynes were quickly frozen at -150 \({}^{\circ}\)C in liquid nitrogen and then stored at -80 \({}^{\circ}\)C [42]. Before the experiments, the larynes were slowly thawed at 6 \({}^{\circ}\)C in a refrigerator. They were then fixated on a 4 mm inside diameter stainless steel tube, which functioned as an artificial trachea. For fixation, a stainless adjustable steel ring was used to prevent air leakage. Rods and positioning screws were used to maintain stable larynx positions, see Figure 1 in [39]. At a distance of 100 mm below the larynx, a hole was drilled in the stainless-steel tube and the pressure sensor was placed there to measure the subglottal pressure. Figure 2 shows the experimental setup. The subglottal pressure data were measured with an XCS-93-5 PSISG pressure sensor (Kulite Semiconductor Products, Inc., Leonia, NJ, USA), which was positioned 100 mm below the larynx on the inside of the stainless-steel tube. The pressure sensor was connected to a PXIe-4330 bridge module (National Instruments, Austin, TX, USA). The acoustic pressure data was measured using a 4189 1/2\" free-field microphone (Bruel & Kjaer, 2850 Naerum, Denmark) mounted above the glottis at a distance of 200 mm and a tilt angle of 45\({}^{\circ}\). The microphone output signal from a Nexus 2690 microphone was then further processed by a PXIe-4492 dynamic signal acquisition module (National Instruments, Austin, TX, USA). Both signals were resolved at 24 bits. The vocal fold vibrations were recorded by a Phantom V2511 high-speed camera (Vision Research, Wayne, NJ, USA) at 8000 frames per second (fps) with a spatial resolution of \(768\times 768\) pixels. The videos were recorded at 16 bits. A Canon EF 180 mm 1: 3.5 L USM macro lens (Canon, Ota, Tokyo, Japan) was used. The subglottal pressure signal as well as the acoustic signal were synchronously sampled at a rate of \(\mathrm{f_{s}=96}\) kHz. For this purpose, a PXIe-6356 multifunctional data acquisition module (National Instruments, Austin, TX, USA) was used. The setup was controlled using the software LabView (National Instruments, Austin, TX, USA). A detailed description of the setup and its control is given in [PERSON] et al. (2017) [43]. Different levels of vocal fold pre-stress were induced by three different weights applied anteriorly to the thyroid cartilage (\(\mathrm{w_{1}=1g}\), \(\mathrm{w_{2}=2g}\), \(\mathrm{w_{3}=5g}\)). The weights were sutured to the thyroid cartilage and used to shift it forward, thereby simulating contraction of the cricothyroid muscle in three different phonatory positions. An MF1 mass flow controller (MKS Instruments, Andover, MA, USA) powered  
Figure 2: Overview of the experimental setup with inscriptions. by a PR4000B digital power supply (MKS Instruments, Andover, MA, USA) was used to generate an airflow passing through the artificial stainless-steel trachea and larynx. That air was humified with water vapor from a Neptune Heated Humidifier (Teleflex, Morrisville, NC, USA), and heated to 37 \({}^{\circ}\)C to simulate physiological in vivo conditions. The HSI technique allows the computation of quantitative, dynamic-based parameters.