Acoustic and Perceptual Comparison of the Immediate Effects of Semi-Occluded Vocal Tract Exercises and Vocal Facilitating Techniques on the Vocal Function of Traditional Iranian Singers With Muscle Tension Dysphonia: A Randomized Clinical Trial.

OBJECTIVE

Traditional Iranian singing involves demanding vocal techniques that increase the risk of muscle tension dysphonia (MTD). This study compared the immediate effects of Semi-Occluded Vocal Tract (SOVT) exercises and Vocal Facilitating Techniques (VFTs) on the vocal function of traditional Iranian singers diagnosed with MTD.

STUDY

DESIGN

Single-session randomized clinical trial.

METHOD: Twenty-six Persian-speaking singers with MTD (mean age = 32.31 ± 5.51 years) were randomly assigned to SOVT (n = 13) or VFT (n = 13) groups. Each participant completed a single 1-hour intervention session including four techniques. Acoustic measures included the Acoustic Voice Quality Index (AVQI) and Acoustic Breathiness Index (ABI), and auditory-perceptual evaluation used the Persian version of the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V). Pre- and post-intervention data were compared using mixed-design repeated-measures ANOVA.

RESULTS

Both groups demonstrated significant improvements in AVQI, ABI, and overall dysphonia severity after intervention (P < 0.05). Between-group comparisons revealed that the SOVT group achieved significantly greater reductions in ABI (P < 0.001), indicating superior improvement in breathiness, while changes in AVQI and dysphonia severity did not differ significantly between groups.

CONCLUSION

Both SOVT and VFT approaches led to immediate improvements in vocal quality among traditional Iranian singers with MTD. While SOVT exercises showed a greater reduction in breathiness, both methods were effective overall. These findings support the clinical utility of both techniques and highlight the potential of SOVT for addressing breathiness. Further research is needed to explore long-term outcomes and integrated treatment strategies tailored to professional voice users.