## 2 Materials and Methods
### Voice Recordings  
All subjects were asked to sustain the vowel /a/ for at least 5 s and to read a Dutch phonetically balanced text at comfortable pitch and loudness. Both types of voice samples were recorded using an AKG C420 head-mounted condenser microphone (AKG Acoustics, Munchen, Germany), digitized at a sampling rate of 44.1 kHz and a resolution of 16 bits using the Computerized Speech Lab model (KayPentax, Lincoln Park, NJ, USA), and saved in WAV-format. The microphone was positioned at 8-10 centimeters and at a 45\({}^{\circ}\) azimuthal angle from the mouth. Recording took place in an anechoic  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**AVQI** & **Language** & **Number of Voice Samples** & **Threshold** & **Sensitivity** & **Specificity** & **Reference** \\ \hline first & Dutch & 251 & 2.95 & 74\% & 96\% & [PERSON] et al. [5] \\ \hline first & Dutch & 39 & 2.95 & 85\% & 100\% & [PERSON] et al. [8] \\ \hline first & Dutch & 50 & 3.19 & 92\% & 73\% & [PERSON] et al. [11] \\ \hline first & Dutch & 50 & 3.66 & 85\% & 80\% & [PERSON] et al. [11] \\ \hline first & German & 50 & 3.05 & 98\% & 75\% & [PERSON] et al. [11] \\ \hline first & French & 50 & 3.07 & 97\% & 70\% & [PERSON] et al. [11] \\ \hline first & English & 50 & 3.29 & 90\% & 90\% & [PERSON] et al. [11] \\ \hline first & English & 50 & 3.25 & 95\% & 82\% & [PERSON] et al. [11] \\ \hline first & German & 61 & 2.70 & 79\% & 92\% & [PERSON] et al. [10] \\ \hline first & Australian English & 107 & 3.46 & 82\% & 92\% & [PERSON] et al. [9] \\ \hline first & Dutch & 60 & 2.80 & 91.7\% & 87.5\% & [PERSON] et al. [15] \\ \hline second 02.02 & Lithuanian & 264 & 3.31 & 71.7\% & 88\% & [PERSON] et al. [20] \\ \hline second 02.02 & Korean & 1.524 & 3.33 & 90.0\% & 96.5\% & [PERSON] et al. [19] \\ \hline second 02.02 & Finnish & 50 & 2.35 & 82.1\% & 95.5\% & [PERSON] et al. [14] \\ \hline second 02.02 & Finnish & 200 & 2.87 & 79.6\% & 86.2\% & [PERSON] et al. [22] \\ \hline second 02.02 & Lithuanian & 264 & 3.31 & 78.1\% & 92.0\% & [PERSON] et al. [18] \\ \hline second 02.02 & Lithuanian & 184 & 2.97 & 83.8\% & 93.7\% & [PERSON] et al. [13] \\ \hline second 02.02 & Japanese & 336 & 3.15 & 72.5\% & 95.2\% & [PERSON] et al. [12] \\ \hline second 02.02 & Dutch & 60 & 2.43 & 100\% & 93.6\% & [PERSON] et al. [15] \\ \hline third 03.01 & Dutch & 1058 & 2.43 & 78.5\% & 93.2\% & [PERSON] et al. [7] \\ \hline third 03.01 & Japanese & 455 & 1.41 & 84.4\% & 85.6\% & [PERSON] et al. [16] \\ \hline third 03.01 & Spanish & 183 & 2.28 & 74.8\% & 94.6\% & [PERSON] et al. [17] \\ \hline third 03.01 & German & 218 & 1.85 & 72\% & 90\% & [PERSON] et al. [21] \\ \hline third 03.01 & French & 120 & 2.33 & 59.8\% & 100\% & [PERSON] et al. [24] \\ \hline third 03.01 & Brazilian Portuguese & 50 & 1.10 & 57.8\% & 100\% & [PERSON] et al. [37] \\ \hline third 03.01 & Brazilian Portuguese & 53 & 1.16 & 86\% & 80\% & [PERSON] et al. [23] \\ \hline third 03.01 & Brazilian Portuguese & 53 & 1.56 & 88.6\% & 100\% & [PERSON] et al. [23] \\ \hline \multicolumn{6}{c}{**Mean**} & 2.67 & \\ \hline \hline \end{tabular}
\end{table}
Table 1: List of acoustic voice quality index (AVQI) thresholds in previous studies, investigating AVQI in different languages, with the version of AVQI used, the language, the number of evaluated voice samples, and sensitivity and specificity level and reference.  
audiometric cabin with a low mean ambient noise of 38 dBA. Vowel samples were edited to include only the medial 3 s and continuous speech samples were cropped to contain only the first two sentences of the speech task.