Fig. 1. Schematization of perceptual evaluation changes: total GRBAS score at baseline and at 2 and 4 weeks after initiation of the study in each group. GRBAS, grade, roughness, breathiness, asthenia, and strain. ^a)p<0.017 by Mann-Whitney U test with Bonferroni correction. ^b)p<0.025 by Wilcoxon signed-rank test with Bonferroni correction.