Randomized controlled trial of vocal function exercises on muscle tension dysphonia in Vietnamese female teachers.

Abstract

This study evaluated the treatment effects of vocal function exercises on muscle tension dysphonia (MTD) in tonal language speakers. Single-blinded, randomized, controlled, clinical trial. Forty female primary school teachers from Northern Vietnam, diagnosed with MTD, were randomly allocated into a treatment group (n = 22), which used a full vocal exercise protocol (FE) (modified for use with Vietnamese speakers), and a control group (n = 18) which was treated with a partial vocal exercise protocol (PE). The treatment duration was 4 weeks for both groups. Acoustic and perceptual data were used as primary outcome measures. Acoustic parameters included frequency and amplitude perturbation, harmonics-to-noise ratio (HNR), mean fundamental frequency of the broken and rising tones, and parameters representing pitch movement in the rising tone. Perceptual analyses were performed on pre- and posttreatment samples of the sustained /a/ sound using anchor vocal samples. Self-report data, collected via a posttreatment questionnaire, comprised the secondary outcome measure. Significant changes in perturbation, HNR, and perceptual data were observed in the FE group but not in the PE group. The FE group showed increased size and speed of pitch change. Participants from both groups showed positive changes in some tonal parameters after treatment. However, the magnitude of change and the number of participants with positive changes were larger in the FE group. The data showed that vocal function exercises may be a cost-effective treatment for MTD.