Validation of Acoustic Voice Quality Index Version 3.01 and Acoustic Breathiness Index in Korean Population

Abstract

This study aimed to verify the Acoustic Voice Quality Index (AVQI) version 3.01 and the Acoustic Breathiness Index (ABI) as tools for acoustic analyses in the Korean language. Concatenated voice samples of sustained vowels (SV) and continuous speech (CS) were collected from 151 subjects with dysphonia and 71 vocally healthy subjects. The overall voice disorder severity (grade [G] and overall severity [OS]) and breathiness severity (B) were subjected to an auditory-perceptual rating by three raters. First, we equalized the proportions of SV and CS with respect to the time lengths of the voice samples to improve the ecological validity. We then validated the AVQI and ABI in the Korean language, using our most recent dataset of 1,667 voice samples. Second, we compared the results of the acoustic analyses between the vocally healthy controls and the dysphonia groups. Third, we confirmed the concurrent validity and diagnostic accuracy using the Spearman rank-order correlation coefficient (rs) and various statistical methods (receiver operating characteristic curve, pairwise comparison, and likelihood ratio [LR] analyses). We observed strong inter-rater reliability for G, B, and OS. Moreover, we identified 26 standardized syllables in the CS samples (3 second voiced segments), which allowed the equalization of both voice tasks. A comparison of the two voice groups revealed statistically significant differences in the AVQI, ABI, G, B, and OS (all P < 0.01). Moreover, we identified strong correlations of the AVQI with G (rs > 0.88, P < 0.01) and OS (rs > 0.84, P < 0.01) and of ABI with B (rs > 0.87, P < 0.01). Finally, we confirmed cutoffs of 3.154 (sensitivity: 90%, specificity: 89%, LR+: 8.45, and LR-: 0.12) and 3.685 (sensitivity: 88%, specificity: 86%, LR+: 6.47, and LR-: 0.14) as optimal predictive powers for AVQI and ABI, respectively. As per our results, in a sample of Korean speakers, the AVQI and ABI exhibited strong concurrent validity for the quantification of dysphonia severity with respect to OS and B. We consider that analyses based on the AVQI and ABI will enable the discrimination and assessment of dysphonia in clinical practice.