Test-retest reliability and discriminatory power of multidimensional voice analysis program

The objectives of this study were to evaluate and compare the test-retest reliability of acoustic parameters (jitter [%], shimmer [%], noise-to-harmonic ratio [NHR], and voice turbulence index [VTI]) by using multidimensional voice program, and to detect the discriminatory power of the acoustic measures with respect to dysphonic voices and normal voices.

Fifty-four (25 male and 29 female) participants with voice disorders and fifty-one (27 male and 24 female) participants with normal voices were enrolled in this study. They were assessed by anamnesis, visual examination, auditory perceptual assessment (GRBAS), and acoustic measurements. The intraclass correlation coefficient was used to determine the test-retest reliability. The effect size (d value) and p value obtained from the t-test were used to determine the discriminatory power.

In the normal group, good reliability was observed for jitter, shimmer, and NHR, and moderate reliability was observed for VTI. With regard to the dysphonic group, jitter, shimmer, and VTI were moderately reliable, and the NHR had good reliability. Meanwhile, the discriminatory powers of jitter and shimmer were evaluated as 'medium', and those of NHR and VTI as 'small'.

The reliability and discriminatory powers of our acoustic measures were high compared with most other studies. Their level of reliability and discriminatory power can be maximised by using stringent rules. However, attaining an excellent level of reliability and discriminatory seems infeasible power owing to the variable characteristic of voice. Therefore, acoustic measures should be adopted as a complementary tool.