Purpose: This study evaluates the effectiveness of two different programs of voice-treatment on a heterogeneous group of dysphonic speakers and the stability of therapeutic progress for longterm follow-up post-treatment period, using a limited multidimensional protocol of evaluation. Method: Forty-two participants with voice disorders were randomly assigned to one of two groups. Participants in group 1 received voice-therapy and participants in group 2 received a vocal-hygiene program. Vocal function was assessed before and after treatment. Results: MANOVA analysis Pillai's trace test shows significant pre-post immediate differences between treatments in favor of direct-intervention. Repeated-measures ANOVAs display significant within subjects main effect for follow-up period in the 8 measures considered. Interaction effects of group x time are also found in five out of the eight continuous variables analyzed (3 aerodynamics-acoustic and 2 self-rating), indicating differences between both treatments. Qualitative dimensions (perceptual, laryngoscopic and spectrographic assessments) also support voice-therapy superiority. Conclusions: Results of this study suggest superiority of a voice-therapy (direct treatment) approach over a vocal-hygiene program (indirect treatment). This advantage is on the majority of the 8 continuous variables analyzed (aerodynamics, acoustic, and self-rating), including qualitative perceptual, laryngoscopic and spectrographic voice-dimensions. The stability of changes is extended during a post-treatment follow-up period.