The effectiveness of voice therapy for patients with non-organic dysphonia.

Forty-five patients diagnosed as having non-organic dysphonia were assigned in rotation to one of three groups. Patients in one group received no treatment and acted as a control group. Patients in the other two groups received a programme of either 'indirect' therapy or 'direct with indirect' therapy, respectively. A self-report questionnaire of vocal performance, observed ratings of voice quality, and computer-derived acoustic measurements (signal-to-noise ratio, pitch perturbation and amplitude perturbation) were carried out on all patients before and after treatment to evaluate the changes in voice quality over time. There was a significant difference between the three groups on the self-report questionnaire, voice quality ratings and pitch perturbation measurements (P = < 0.05). Thirteen out of 15 control patients showed no significant change on any of the measures. Seven patients who received indirect treatment showed significant improvement in voice quality following treatment. Fourteen out of 15 patients who received direct treatment showed significant improvement in voice quality.