Influence of the Voice Sample Length in Perceptual and Acoustic Voice Quality Analysis.

OBJECTIVE

To analyze the variations that different voice sample length (VSL) has on the perceived degree of voice quality deviation and on the Acoustic Voice Quality Index (AVQI) accuracy.

METHODS

Voices of 71 subjects (53 dysphonic; 18 vocally health) were recorded: numbers 1-20 (42 syllables) + vowel/a/. Three different VSL were edited: VSL_long, 1-20 + 3 seconds vowel/a/; VSL_cust, customized length, were voiced-segments of the continuous speech had the same length of the vowel (mean = 18.73 syllables corresponding to 3 seconds of only-voiced segments) + 3 seconds vowel/a/; VSL_short, 1-10 (15 syllables) + 3 seconds vowel/a/. Three voice specialists perceptually judged the overall voice quality (G); 3 sessions were performed to evaluate each VSL variant. AVQI's precision and Spearman correlation were assessed.

RESULTS

The intra-rater reliability was "almost perfect" (kappa >0.826) for all evaluators in VSL_short; "substantial" (0.684) and "almost perfect" (0.897) in VSL_cust and "fair" (0.447) to "almost perfect" (1.000) in VSL_long. The inter-rater reliability was "moderate" (0.554) for VSL_long, "substantial" (0.622 and 0.618) for VSL_cust and VSL_short. The Gmean and AVQI_mean were perceived as more severe for longer samples and less severe for shorter samples. Considering the AVQI, VSL_short (r = 0.665) presented the higher correlation. VSL_cust presented the best area under the ROC curve (0.821). VSL_long and VSL_cust specificity was 100%, VSL_short specificity was 75%; higher sensitivity was observed for VSL_short (74%).

CONCLUSION

The voice quality outcomes changes for different VSLs. Longer VSLs seem to be perceived as more deviated, shorter VSLs seem to be more reliable and have better correlation with the acoustic analysis. The AVQI best accuracy was found at a customized length. Thus, to increase the voice analysis reliability, standardized procedure must be followed, including a precise speech material control allowing comparison among clinics and voice-centers.