How Do Tube Diameter and Vocal Tract Configuration Affect Oral Pressure Oscillation Characteristics Caused by Bubbling During Water Resistance Therapy?

A secondary objective was to examine the degree of self-perceived sensation of massage-like effect produced by bubbles during WRT. Methods: Forty-two participants were included in this study. Assessment protocol included: (1) self-assessment of massage-like sensation and (2) objective assessment of air pressure-related variables. In the first section, participants were instructed to select and produce a sustained-vowel like phonation into three different tubes (varying inner diameter) submerged 5 cm below the water surface. Also, two different vocal tract configurations were produced by all subjects: (1) horizontal position (regular vocal tract position), (2) vertical position (yawning position with low vertical laryngeal position). Participants were asked to self-assess their massage-like sensation. In the second section, objective measurements of air pressure-related variables were acquired during WRT exercises. Results: Statistical differences were driven by tube inner diameter for oral pressure oscillation frequency, amplitude, jitter and shimmer and self-perceived massage-like sensation. Vocal tract position generated differences for medium-size tube and large-size tube only for self-perceived massage-like sensation. Conclusion: Inner diameter of tube and configuration of vocal tract affect bubble characteristics and massage-like sensation during WRT. Larger tube diameters and vocal tract volumes seem to produce more regular bubbles, lower bubble frequency, and larger bubble amplitude, causing a more evident massage-like sensation. Therefore, control of these variables is apparently relevant to obtain the best effect in patients with voice disorders.