Cross-Validation of Acoustic Roughness Index in Korean

The Acoustic Roughness Index (ARI) is a multivariate acoustic measure specifically developed to objectively quantify vocal roughness by integrating multiple acoustic features, including subharmonic phenomena that are difficult to capture using conventional acoustic measures. Because the ARI analyzes concatenated voice samples that include connected speech, its performance may be influenced by language-specific phonetic and prosodic characteristics. Although its clinical utility has been demonstrated in Japanese and German populations, it has not been validated in Korean speakers. Therefore, this study aimed to validate the ARI and establish an optimal diagnostic cutoff for discriminating dysphonic voices from normal voices in Korean speakers.

Voice recordings from 330 native Korean speakers (74 controls and 256 patients with dysphonia) were analyzed. Concatenated voice samples consisting of a sustained vowel and a reading passage were used to calculate ARI scores. Three experienced speech-language pathologists independently rated vocal roughness using a 7-point auditory-perceptual scale, and the mean rating served as the reference standard. Concurrent validity was evaluated using Spearman's rank correlation, and receiver operating characteristic (ROC) curve analysis was performed to determine the optimal diagnostic cutoff.

ARI demonstrated a strong positive correlation with auditory-perceptual roughness ratings (Spearman's ρ = 0.804, P < 0.001). ARI scores were significantly higher in the dysphonia group than in the control group (P < 0.001). ROC analysis demonstrated excellent diagnostic accuracy (AUC = 0.923), and the optimal cutoff value was 2.29, yielding a sensitivity of 74.6% and a specificity of 90.5%.

The ARI demonstrated strong concurrent validity and excellent diagnostic performance for discriminating dysphonic voices from normal controls in Korean speakers. The proposed cutoff of 2.29 provides clinically useful discrimination and supports the cross-linguistic applicability of the ARI as an objective adjunct to auditory-perceptual voice assessment.