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

Abstract

Semi-occluded vocal tract exercises (SOVTE) may improve the source and filter interaction 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. Eighteen (eight men; 10 women), ages 18-50, with behavioral dysphonia participated in this randomized 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 analysis, vocal fatigue index (VFI), self-perceived resonant voice, and vocal handicap index-30 (VHI-30) were measured 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. 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. 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.