Multidimensional Comparison of Immediate Effect of Semi-Occluded Vocal Tract Exercises and Vocal Facilitating Techniques on Vocal Function of Speech-Language Pathologists With Vocal Fatigue: A Randomized Clinical Trial.

Abstract

Objectives: Vocal fatigue is a common hyperfunctional voice condition, particularly among speech-language pathologists (SLPs), due to their high vocal demands. This study compared the immediate effects of semi-occluded vocal tract (SOVT) exercises and vocal facilitating techniques (VFTs) on the vocal function of SLPs with vocal fatigue, emphasizing multidimensional voice assessments.

Study design: Single-blind randomized clinical trial.

Methods: Twenty-six SLPs and senior speech therapy students with vocal fatigue were randomly assigned to SOVT or VFT groups. Participants performed four techniques for approximately 40 minutes. Vocal outcomes, including single-dimension (jitter, shimmer, harmonic-to-noise ratio [HNR], and Cepstral Peak Prominence Smoothed [CPPS]) and multiparametric (Acoustic Voice Quality Index [AVQI], Acoustic Breathiness Index [ABI]) acoustic measures, as well as maximum performance task and auditory-perceptual parameters, were evaluated before and immediately after treatment. Within-group and between-group comparisons were conducted.

Results: SOVT exercises significantly improved single-dimension acoustic parameters, including jitter, shimmer, and HNR and auditory-perceptual dysphonia severity within the group (P < 0.05). Between-group analysis showed a greater reduction in jitter and auditory-perceptual severity in the SOVT group compared with the VFT group (P < 0.05). However, multiparametric acoustic indices, including AVQI and ABI, showed no significant changes in either group, suggesting that longer interventions may be necessary to impact connected speech.

Conclusions: SOVT exercises showed immediate improvements in acoustic and auditory-perceptual measures for SLPs with vocal fatigue, making them a promising short-term intervention. However, while sustained vowel analysis revealed significant changes, connected speech analysis did not show similar improvements, highlighting the importance of assessing real-world vocal function. In contrast, VFT techniques likely require longer durations to yield significant effects. Future research should explore extended treatments with multiparametric measures to better understand their efficacy for professional voice users.