Validity and reliability of acoustic voice quality index in Turkish

Acoustic voice analysis is a non-invasive method, which objectively measures the dysphonia severity. Traditionally, acoustic measures are derived from only sustained vowels. However, in acoustic measures, combining sustained vowel and continuous speech parts has shown to be more reliable and valid. Acoustic Voice Quality Index (AVQI) is a multivariate tool based on the integration of sustained vowel and continuous speech parts, yielding a single score between 0 and 10 for the overall voice quality. The aim of this study was to investigate the validity and reliability of AVQI version 2 (AVQI 02.06) in Turkish language. A total of 255 subjects with dysphonia (n = 127) and with normal voices (n = 128) were asked to sustain the vowel /a/ and read aloud the phonetically balanced text to conduct the AVQI analysis. To determine the test-retest reliability of AVQI, 40 subjects were reassessed after the first AVQI determination. To explore the criterion-related concurrent validity of AVQI and auditory-perceptual analysis, all the voice samples were judged by 5 raters with auditory-perceptual evaluation. The inter-rater and intra-rater reliability of the judges were calculated. The correlation between AVQI scores and subjective tests were also evaluated. The results of this study revealed an excellent test-retest reliability of AVQI and there was a statistically significant positive correlation between AVQI and auditory-perceptual evaluation and subjective tests. The threshold value for dysphonia was 2.98 in Turkish language. AVQI is a valid and reliable tool in differentiating dysphonic and normal voice in the Turkish speaking population.