Accuracy of Acoustic Voice Quality Index and Its Isolated Acoustic Measures to Discriminate the Severity of Voice Disorders.

Objective: To evaluate the Acoustic Voice Quality Index (AVQI) and its isolated acoustic measures accuracy in discriminating voices with different degrees of deviation.

Methods: Two hundred and fifty-eight voice samples (160 dysphonic; 98 vocally healthy). Information regarding acoustic analysis and overall degree of deviation (G) were considered. The acoustic analysis consisted of the AVQI total score and its isolated acoustic measures: smoothed cepstral peak prominence (CPPs); harmonic-to-noise ratio (HNR); shimmer local and dB (Shim, ShdB); the general slope of the spectrum (Slope) and tilt of the regression line through the spectrum (Tilt). The auditory-perceptual judgment was the median G score of five voice specialists (Cohen's = 0.605-0.773; Fleiss = 0.370). Quadratic discriminant analysis and accuracy, sensitivity, and specificity of performance measures were used to investigate the discriminatory power of these measures.

Results: AVQI presented acceptable accuracy to differentiate voices with no vocal deviation and with vocal deviation (73.9%) and among the degrees of deviation (mild vs. moderate = 70.49%; mild vs. moderate = 71.39%; moderate vs. severe = 87.5%). No isolated acoustic measurement was consistent with differentiating voice quality among all degrees of deviation. A combination of five acoustic measures (CPPs, HNR, ShdB, Slope, Tilt) had the highest accuracy to differentiate between healthy and deviated voice (75.55%). Shimmer was more accurate to discriminate between voices with mild, moderate, and severe deviation; almost all isolated acoustic measurements were accurate to discriminate voices with moderate and severe deviation. The combination of acoustic measures presented higher accuracy (mild vs. moderate = 70.21%-74.29%; mild vs. moderate = 71.53%-76.11%; moderate vs. severe = 86%-95.50%).

Conclusion: AVQI is an accepted tool to discriminate among different degrees of vocal deviation, and more accurate between voices with moderate and severe deviations. Isolated acoustic measures perform better when discriminating voices with a higher degree of deviation. A combination of acoustic parameters, with the same weight, is more accurate to discriminate different degrees of deviation, however, not consistent.