A randomized controlled trial of stretch-and-flow voice therapy for muscle tension Dysphonia

Objectives To investigate the effect of stretch-and-flow voice therapy on vocal function and handicap. Study Design Randomized controlled trial. Methods Participants with primary muscle tension dysphonia were randomly assigned to experimental or control groups. Experimental participants received vocal hygiene education followed by 6 weeks of stretch-and-flow voice therapy. Control participants received vocal hygiene education only. Outcome variables consisted of a measure of vocal handicap (Voice Handicap Index [VHI]), maximum phonation time, s/z ratio, and acoustic measures. All measures were obtained at baseline prior to treatment and within 2 weeks posttreatment or at the end of the control period. The pre- to posttreatment measurement change (delta Δ) was applied to statistical analyses. Results A multivariate analysis of variance revealed significant group differences in pre-to-post changes on measures of VHI, maximum phonation time, and cepstral peak prominence (CPP) in connected speech and vowels (P-=-0.003, 0.013, 0.025, and 0.017 respectively), with a significant reduction of VHI (Cohen's d-=-1.6), increase in maximum phonation time (Cohen's d-=-1.2), increase of CPP in connected speech (Cohen's d-=-1.2), and increase of CPP in vowels (Cohen's d-=-1.1) in the experimental group compared to the control group. Conclusions This preliminary small sample randomized controlled trial found significantly greater improvement in vocal handicap, maximum phonation time, and acoustic measures of vocal function after participants received stretch-and-flow voice therapy compared to participants receiving vocal hygiene education alone. Additional research incorporating larger samples will be needed to confirm and further investigate these findings.