The effect of changes in velopharyngeal orifice area on vowel intensity.

This investigation studied the influence of changes in velopharyngeal orifice size on vowel intensity in normal speakers when subglottal air pressure was controlled. Controlled variations in velopharyngeal orifice area were achieved by two different methods. The effective velopharyngeal orifice areas introduced into the subjects were verified aerodynamically. A reduction in vowel intensity (SPL) was recorded during the large experimental velopharyngela orifice condition (50 mm2) when compared to a control condition. The clinical implications of these findings are discussed.