Measurement of velopharyngeal closure force during vowel production

The purposes of this study were to (a) design and test a new velopharyngeal closure force sensing bulb, and (b) use the closure force bulb to gather additional information on the variations in closure force associated with different vowels. The closure force sensing bulb possessed a flat frequency response to 30 Hz. Its output was highly linear relative to applied gram force. Reliable placement of the bulb in human subjects was achieved following prescribed placement criteria. The bulb was sensitive to small variations in velopharyngeal closure force. In agreement with some previous reports, high vowels were associated with greater velopharyngeal closure forces than low vowels. The results of this investigation support the notion that articulatory goals are specified for vowels. This vowel specificity was observed during production in both isolation and in context.