Perceptual characteristics of adductor spasmodic dysphonia.

The evaluation of perceptual symptoms is one of the mainstays in the diagnostic workup of adductor spasmodic dysphonia (ADSD). The most widely used perceptual rating system is the GRBAS scale. However, with this system, not all audible features of ADSD can be described. Therefore, we extended the GRBAS system by 6 parameters. The aim of this study was assessment of the perceptual characteristics of ADSD with the "extended" GRBAS system and evaluation of its reproducibility. Seventy-seven patients were scored independently by 3 experienced observers quantifying the voice sound profile. Cluster analysis distinguished 4 different voice types. Intraobserver and interobserver agreement among 8 less-experienced observers appeared fair-to-good. This study demonstrates that the "extended" GRBAS system is suitable for perceptual characterization of ADSD. On the grounds of the fair-to-good interobserver variability, it is appropriate for clinical use. Moreover, 4 different voice clusters of ADSD were identified, with significant differences in voice and demographic parameters.