Efficacy of a Semi-Occluded Vocal Tract Exercises-Therapeutic Program in Behavioral Dysphonia: A Randomized and Blinded Clinical Trial

Purpose. Semi-occluded vocal tract exercises (SOVTE) may improve the source and filter interac-tion by changing the acoustic characteristics and the impedance of the vocal tract, both in dysphonic and vocally healthy populations. However, there are a few studies that verify the effects of these exercises in a clinical trial. Thus, this study's purpose was to analyze the effectiveness of the SOVTE-Therapeutic Program (SOVTE-TP) in vocal quality and self-assessment, comparing it with Vocal Function Exercises.Method. Eighteen (eight men; 10 women), ages 18-50, with behavioral dysphonia participated in this random-ized and blinded clinical trial. The participants were equally randomized into two groups: Experimental Group and Vocal Function Exercises Group. They were assessed at three moments: before the treatment, after finishing it, and one month after finishing the treatment--follow up. Acoustic measures (ie, fundamental frequency, jitter, shimmer, noise-to-harmonic ratio, cepstral peak-smoothed, alpha ratio, and L1-L0), auditory-perceptual analy-sis, vocal fatigue index (VFI), self-perceived resonant voice, and vocal handicap index-30 (VHI-30) were mea-sured at all assessment moments. For the two groups, the interventions happened twice per week (four weeks) and lasted 35 minutes. It was applied the repeated-measures ANOVA test (P< 0.05) and Tukey Test.Results. The acoustic measures and auditory-perceptual had no differences between the groups and moments, respectively, which means that SOVTE-TP did not cause any harm. The auditory-perceptual analysis showed a mild deviation of participants' vocal quality. All groups reduced the VFI and VHI-30 scores in M2 and kept these results at M3 also, the vocal economy sensation increased in M2, decreasing slightly in M3.Conclusion. SOVTE-TP has positive effects regarding self-assessment (VFI, VHI, and resonant voice quality) on patients with mild behavioral dysphonia, and it provides the same effects as VFE.