Air-pressure, Vocal Fold Vibration and Acoustic Characteristics of Phonation during Vocal Exercising. Part 1: Measurement in Vivo

The study investigates differences between three most widely used methods in voice training and therapy: Phonation into a resonance tube with the outer end in the air or submerged 2–10 cm in water (‘water resistance therapy’ with bubbling effect), and phonation into a very thin straw. One female speech trainer served as subject. Acoustic and electroglottographic (EGG) signals, and both mean and dynamic air pressures in the mouth cavity were registered for repetitions of [pu:pu], and for phonation into the tubes, while the outer end was randomly shuttered, in order to get an estimate of subglottic pressure. Soft and normal phonations were recorded. Phonation threshold decreased with tube in air, suggesting that increased input reactance assists small amplitude oscillation of the vocal folds. Oral pressure (Poral) increased with increasing impedance offered by the tube and straw, most when the tube was 10 cm in water. In most cases subglottic pressure (Psub) increased relatively more than Poral, so that transglottic pressure (Ptrans) was higher in the exercises compared to vowel. Contact quotient (CQ) from EGG increased, which may be due to increased Ptrans. In tube 10 cm in water Ptrans decreased and CQ increased suggesting increased adduction as compensation. Exercises that increase oral air-pressure offer a possibility to train glottal and respiratory adjustments under the influence of increased flow resistance which may prevent excessively strong vocal fold collisions.