Experimental validation of repeated /pa/ gestures for estimation of subglottal pressure with incomplete glottal closure*

Clinical estimation of subglottal pressure is a crucial metric for evaluating vocal efficiency, but remains difficult to quantitatively measure. Protocols for estimating subglottal pressure rely upon vocalizations where /pa/ is repeatedly phonated at a constant phonatory effort, and the intraoral pressure is recorded. It is assumed that the occluded intraoral pressure is the same as the subglottal pressure during the phonatory segment. The validity of this approach has been questioned in scenarios where incomplete glottal closure allows persistent flow leakage across the vocal folds, thereby changing the time-averaged flow resistance. In response, a benchtop synthetic vocal fold flow facility is utilized to quantify the temporal response of subglottal and supraglottal pressures during a simulated /pa/ gesture with leakage flow. Vocal efficiency and the time constant of the intraoral pressure response are quantified as a function of posterior glottal opening area. The results provide insight into clinical considerations that arise when estimating subglottal pressure with incomplete glottal closure, as well as the accuracy of this approach.