Validation of the Acoustic Voice Quality Index Version 03.01 and Acoustic Breathiness Index in German.

OBJECTIVE: The aim of this study was to validate the acoustic voice quality index (AVQI) version 03.01 and the acoustic breathiness index (ABI) in the German language.

METHODS: Concatenated voice samples of continuous speech (cs) and sustained vowel (sv) [a:] from 175 subjects with dysphonia and 43 vocally healthy subjects were perceptually judged for overall voice quality and breathiness severity. First, to reach a higher level of ecological validity, the proportions of cs and sv were equalized regarding the time length. Second, concurrent validity and diagnostic accuracy were statistically verified using the Spearman rank-order correlation coefficient (rs ) and several estimates of the receiver operating characteristics, likelihood ratio, and Youden index.

RESULTS: A moderate reliability of overall voice quality and breathiness severity from three experts were found. It was found that 27 syllables as standardization of the cs part, which represents 3 seconds of voiced cs, allows the equalization of both speech tasks. A strong correlation was revealed between AVQI and overall voice quality (rs  = 0.86, P < 0.01), and ABI and perceived breathiness severity (rs  = 0.85, P < 0.01). Additionally, the best diagnostic outcome for AVQI and ABI was identified at a threshold of 1.85 (sensitivity of 72 % and specificity of 90 %) and 3.42 (sensitivity of 72 % and specificity of 95 %), respectively.

CONCLUSION: AVQI and ABI showed in the German language valid and robust results to quantify abnormal voice qualities regarding overall voice quality and breathiness severity.