A new technique for measuring velopharyngeal orifice area during sustained vowel production: an application of aerodynamic forced oscillation principles.

A new technique for measuring velopharyngeal orifice area during sustained vowel production is described. The technique is based on a simple oscillatory flow balancing procedure between two aerodynamic branches, a mechanical model of the human upper airway and the subject's upper airway. The area of the velopharyngeal orifice in the model is adjusted until identical oscillatory flows traverse it and the subject's velopharyngeal orifice in response to a common forced oscillatory pressure. When identical oscillatory flows are observed, the area of the adjusted orifice is taken as a measure of the area of the subject's velopharyngeal orifice.