Effects of Voice Therapy using Semi-Occluded Ventilation Mask and Speech Tasks on Adults with Vocal Fatigue

Objectives: This study aimed to investigate the vocal changes in adults experiencing subjective vocal fatigue through a three-week intervention employing a semi-occluded ventilation mask (SOVM), which is a type of semi-occluded vocal tract exercise (SOVTE), and Korean speech materials. Methods: We implemented a three-week intervention program using an SOVM and a protocol based on Korean speech materials for 22 Korean adults (5 males and 17 females, aged 25.81 +/- 7.31 years) reporting subjective vocal fatigue. The SOVM was fabricated by establishing a semi-occluded environment using a silicone plug with a central hole, which was inserted into the front opening of an air-cushion mask, typically used in medical context. Participants were also instructed to perform home training sessions twice a day until the subsequent intervention. The outcomes of multi-dimensional voice evaluations were compared pre- and post-intervention to assess vocal changes. Results: Post-intervention, significant improvements were observed in specific acoustic measurements (jitter percent, shimmer percent, noise-to-harmonic ratio, and cepstral peak prominence of vowel phonation) and the severity indices derived from those acoustic parameters. Additionally, a significant reduction in patient-reported outcome measures was noted following the intervention. Conclusion: The findings suggest that voice intervention using the SOVM and Korean speech materials has the potential to alleviate vocal fatigue and enhance vocal quality in individuals with vocal fatigue complaints.