Differentiated perceptual evaluation of pathological voice quality: reliability and correlations with acoustic measurements.

The perceptual GRBAS scale for deviant voice quality (completed with a "I" parameter: Instability = fluctuation of voice quality over time) was tested in 5 different institutes on 943 voice patients. Each voice was evaluated separately by 2 professionals. The interrater correlation reaches 0.87 for G (grade), 0.70 for R (roughness), 0.69 for B (breathiness) and 0.65 for A/S (asthenicity/strain). Experience with the scale significantly improves the interrater agreement. The intrarater correlation (80 voices; time interval 2-6 months) is systematically slightly stronger than the interrater correlation. Further, GIRBAS/acoustical correlations were investigated on 80 pathological voices, by using the Multidimensional Voice Program (MDVP) of Kay. Principal component analysis allows reduction of 21 MDVP parameters to 5 clinically relevant aspects, with a typical acoustical measurement for each of them. The strongest correlations are found between G and Shimmer/Noise to harmonics ratio, R and Jitter, and B and Shimmer. As tremor and diplophonia are easily identified perceptually and acoustically, it seems useful to add this information respectively to AS and R. The GIRBAS scale seems to be a valuable instrument for clinical practice.