Validation of the Acoustic Voice Quality Index in the Japanese Language

Objectives. The Acoustic Voice Quality Index ( AVQI) is a multivariate construct for quantification of overall voice quality based on the analysis of continuous speech and sustained vowel. The stability and validity of the AVQI is well established in several language families. However, the Japanese language has distinct characteristics with respect to several parameters of articulatory and phonatory physiology. The aim of the study was to confirm the criterion-related concurrent validity of AVQI, as well as its responsiveness to change and diagnostic accuracy for voice assessment in the Japanese- speaking population. Study Design. This is a retrospective study. Methods. A total of 336 voice recordings, which included 69 pairs of voice recordings ( before and after therapeutic interventions), were eligible for the study. The auditory- perceptual judgment of overall voice quality was evaluated by five experienced raters. The concurrent validity, responsiveness to change, and diagnostic accuracy of the AVQI were estimated. Results. The concurrent validity and responsiveness to change based on the overall voice quality was indicated by high correlation coefficients 0.828 and 0.767, respectively. Receiver operating characteristic analysis revealed an excellent diagnostic accuracy for discrimination between dysphonic and normophonic voices ( area under the curve: 0.905). The best threshold level for the AVQI of 3.15 corresponded with a sensitivity of 72.5% and specificity of 95.2%, with the positive and negative likelihood ratios of 15.1 and 0.29, respectively. Conclusions. We demonstrated the validity of the AVQI as a tool for assessment of overall voice quality and that of voice therapy outcomes in the Japanese- speaking population.