The Linearity of the Relationship Between Articulation Errors and Velopharyngeal Incompetence

Abstract

The inference can be made from research findings and clinical observations that velopharyngeal incompetence is causally related to the artic— ulation errors of individuals with cleft palates; that is, cleft palate speakers with velopharyngeal incompetence are not able to impound and maintain the intraoral pressure required for the production of most consonant sounds. In light of such a relationship between velopharyngeal incompetence and articulation errors, one would expect to obtain rela— tively high correlation coefficients between these two variables. Such is not the case. In general, the correlation coefficients range from .08 (4) to .78 (2) with the majority of the coefficients reported in the range of .30 to .50 (1, 6, '7, 8). The wide variation in the coefficient values can perhaps best be accounted for by the equally Wide variation in the techniques used to arrive at these correlations: some investigators have used pressure measures to assess velopharyngeal incompetence while others have used radiographic films and a variety of measures of articu— lation skills have been used. There are several possible explanations for the lowness of the cor— relations. a) The relationship is no stronger than has been reported. This would indicate that variables other than velopharyngeal incompetence are important in influencing articulation proficiency. b) The available research tools are not sensitive or reliable enough to provide information that would result in higher coeflicients. c) The technique used to assess this relationship has not been appropriate for the existing relationship. In most instances a Pearson product-moment correlation technique which is appropriate only for linear data has been used. Several researchers have suggested that velopharyngeal competence may be dichotomous in its relationship to articulation proficiency or that the relationship be— tween the two variables may be nonlinear. If such were the case, the Mrs.