The Correlation between Nasalance and a Differentiated Perceptual Rating of Speech in Dutch Patients with Velopharyngeal Insufficiency

Abstract

Objective: The correlation between the nasalance score and the perceptual rating of several aspects of speech of speakers with velopharyngeal insufficiency (VPI) by six speech-language pathologists was evaluated. Procedure: The overall grade of severity, hypernasality, audible nasal emission, misarticulations, and intelligibility were rated on visual analog scales. Speech samples with a normal distribution of phonemes (normal text [NT]) and those free of nasal consonants (denasal text [DT]) of 43 patients with VPI were used. Mean nasalance scores were computed for the speech samples, and Spearman correlation coefficients were computed between the mean nasalance score and the five parameters of the differentiated rating. Setting: The Institute of Phoniatrics, Utrecht University Hospital, The Netherlands. Results: The correlation coefficient between the mean nasalance and the perceptual rating of hypernasality ranged among judges from .31 to .56 for NT speech samples and .36 to .60 for DT speech samples. Only small differences were found between speech pathologists with and without expertise in cleft palate speech. The rating of the overall grade of severity appeared to correlate quite well with the rating of the intelligibility (rNT = .77, rDT = .79). Lower correlation coefficients, ranging from .34 to .71, were found between overall grade of severity and hypernasality, audible nasal emission, and mis-articulations. Conclusions: A low correlation between the nasalance and the perceptual rating of hypernasality was found. The parameter overall grade of severity appeared to be determined mainly by the parameter intelligibility. Expertise in rating of cleft palate speech does not guarantee a high correlation between instrumental measurement and perceptual rating.