An Exploratory In Vitro Study of the Effect on Pharyngograms of Acoustic Leaks Through the Velopharyngeal Port

Study Objectives: A nasopharyngeal seal of the velopharyngeal port is important during swallowing and speaking. An acoustic leak through an open velopharyngeal port has also been reported as a source for overestimations of acoustic pharyngograms. Quantitative data on the effects of the size of the acoustic leak on the pharyngogram has not been published. The current exploratory in vitro study was designed to measure the effects of increasing sizes of a nasopharyngeal acoustic leak on the pharyngogram. Methods: A plastic cast of the human upper airway constructed from a postmortem anatomic casting without a nasal cavity was used in the study. Acoustic leaks through a velopharyngeal port, created ~9 cm from the mouth, were mimicked using 12 different sizes of an open velopharyngeal port with areas ranging from 7.1 mm 2 to 1.54 cm 2 . Nasal cavities of either 20 mL or 30 mL were attached to the open velopharyngeal port. Acoustic pharyngometry was used to measure the size of the cast and the nasal cavities per each open velopharyngeal port size in terms of cross-sectional areas (CSA1-2) and volume (area under the curve; AUC1-3).