Comparative Study of Two Semi-Occluded Vocal Tract Protocols: A Randomized Clinical Trial

Area of Science:

• Speech and Hearing Sciences
• Otolaryngology
• Rehabilitation Medicine

Background:

• Semi-occluded vocal tract exercises (SOVTEs) are standard therapeutic interventions for voice disorders, aiming to increase upper airway resistance.
• Two prominent SOVTE protocols, flow-resistant tube (FRT) and Lessac-Madsen Resonant Voice Therapy (LMRVT), are widely utilized.

Purpose of the Study:

• To conduct a randomized controlled trial comparing the efficacy of FRT and LMRVT in patients with voice disorders.
• To perform a noninferiority analysis of FRT against LMRVT.
• To investigate the impact of therapy duration (4 vs. 8 weeks) on outcomes.

Main Methods:

• Sixty-seven participants with voice disorders were randomized into five groups: 4-week FRT, 8-week FRT, 4-week LMRVT, 8-week LMRVT, and a control group.
• Voice Handicap Index (VHI) and Vocal Fatigue Index were assessed pre- and post-treatment.
• Acoustic Voice Quality Index was used for acoustic analysis; linear regression and noninferiority tests were applied.

Main Results:

• Both 8-week FRT and 8-week LMRVT significantly reduced VHI scores compared to controls.
• 4-week FRT also showed a significant VHI reduction versus controls, while 4-week LMRVT did not reach statistical significance.
• FRT was found to be noninferior to LMRVT using a 10-point margin for VHI reduction.

Conclusions:

• Both FRT and LMRVT are effective in improving VHI scores in individuals with voice disorders.
• FRT is a viable alternative to LMRVT, offering comparable efficacy.
• Therapy duration of 4 or 8 weeks did not yield statistically significant differences in VHI scores for either protocol.