The improvement of internal consistency of the Acoustic Voice Quality Index

This investigation aims to explore the improvement of the relatively new hoarseness severity quantification method, called Acoustic Voice Quality Index (AVQI), which measures the concatenation of continuous speech (CS) and sustained phonation (SP) segments. Earlier investigations indicated that the proportion of the SP is more dominant in the final AVQI result than the CS.

Sixty voice samples were selected with different voice pathologies and equal distribution of hoarseness severity ranged from normal to severe. Every voice sample varied in three different durations: voice duration-one (VD-1) with seventeen syllables text plus three seconds of SP, voice duration-two (VD-2) with customized length of CS plus three seconds of SP, and voice duration-three (VD-3) with a whole text plus three seconds SP. All voice samples were perceptually judged on overall voice quality by five experienced voice clinicians. AVQI's precision and concurrent validity were assessed in all three VDs. Finally, the internal consistency across all three VDs was analyzed.

No significant differences were found in the perceptual evaluation of overall voice quality across all three VDs by acceptable rater reliability. The concurrent validity distinguished in all three VDs as a marked degree of correlation (i.e., ranged from rs=0.891 to rs=0.929) with no significant differences across all three VDs. The best precision was found in VD-2. Finally, the internal consistency showed in VD-2 a balanced out impact of the final AVQI score with no significant differences from both speech tasks.

Although AVQI currently uses the speech material of VD-1, the present study demonstrated the best results in VD-2 (i.e., precision and internal consistency). These features of VD-2 facilitate higher representativity and improve the validity of this objective diagnostic instrument.