Objective: Semi-occluded vocal tract (SOVT) exercises have gained increasing popularity in clinical voice therapy due to their perceived therapeutic benefits. However, the specific vocal fold vibratory mechanisms underlying these effects require further investigation. This study aims to investigate vocal fold vibratory patterns before, during, and after the use of various SOVT techniques.
Methods: High-speed recordings was captured using flexible laryngoscope coupled to a high speed camera. Recordings were done to assess vocal fold vibrations before, during, and after water resistance straw phonation, Acapella device, and standard straw phonation. Participants are instructed to sustain the vowel /i/ at a comfortable pitch and loudness for two seconds, producing at least two tokens per condition. The recorded laryngeal images are subsequently analyzed using Kay’s Image Processing Software (KIPS) to evaluate vibratory patterns. Digital Kymography (DKG) is plotted for voice onset, steady state and voice offset to compare the differences between each of the three tokens.
Results: In this pilot study with one vocally trained subject, distinct differences in vocal fold vibratory patterns were observed across three time points: before, during, and after SOVT practice. Notably, the pre-SOVT condition demonstrated reduced opening phases in cycle-to-cycle vibration analysis, suggesting a more pressed phonatory pattern. In contrast, the during- and post-SOVT conditions exhibited larger opening phases and smoother onsets, particularly pronounced during SOVT practice. These findings indicate immediate effects of SOVT on vocal fold dynamics.
Conclusion: This pilot study successfully identified notable changes in vocal fold vibratory patterns using a high-speed imaging system, highlighting the immediate impact of SOVT practices. These findings support the effectiveness of SOVT exercises on vocal fold vibration dynamics. Further research is warranted to deepen our understanding of various SOVT techniques and their specific effects on vocal function.