Varying Supraglottic Pressure Using Controlled Supraglottic Pressure Phonation with a Straw-Shaped Mouthpiece in Healthy Subjects

Abstract

Objective: The objective of this study is to expand on a novel method for semioccluded vocal tract therapy (SOVT) called controlled supraglottic pressure phonation, and investigate the mechanism that introduced supraglottic pressure mediates a decrease in impedance during SOVT therapy. Instead of the previously used CPAP mask, this study analyzes controlled supraglottic pressure phonation by use of a straw mouthpiece to deliver supraglottic pressure.

Methods: Twenty-six human subjects were randomly assigned to one of four supraglottic pressure levels: 0, 2, 4, and 6 cm H₂O, which were controlled through a continuous positive airway pressure device. Subjects were asked to phonate during a SOVT task for one round (referred to as the "short-duration" task) and eight rounds (referred to as the "long-duration" task), in which acoustic and aerodynamic properties were measured before and after. Subjects were surveyed for the levels of discomfort experienced during controlled supraglottic pressure phonation therapy and subjective levels of improvement of vocal economy.

Results: Significant differences were observed between pre- and post-task measurement for phonation threshold pressure for the long-duration task for the 2 cmH₂O group. Frequency measurement was not found to have statistically significant differences. The perceived phonatory effort was not significantly different at any pressure levels.

Conclusions: Lower supraglottic pressure levels will improve ease of phonation for longer durations, however, shorter-duration tasks will not be effective. Controlled supraglottic pressure phonation coupled with straw phonation may produce an improved vocal economy for those who have access to an oppositional airflow setup.

Keywords: Continuous positive airway pressure; Impedance; Phonation threshold pressure; Semioccluded vocal tract; Supraglottic pressure; Voice.