A Word Intelligibility Approach to the Study of Speech Change in Oral Cleft Patterns

Abstract

Although the attainment of speech adequacy has been a primary aim in the habilitation of children born with oral clefts and palatopharyngeal insufficiency, clinical observation suggests that the majority of these indi— viduals do not achieve 'normal' speech. The burden of proof to demonstrate the effectiveness of therapy for oral cleft patients is increasing, and a prerequisite for this is the development of meaningful procedures for studying changes in speech behavior. A number of studies with cleft palate subjects have been reported recently in which listeners made value judgments regarding speech changes which followed therapeutic procedures (4, 8, 11). This approach has a certain logical validity since, in the final analysis, the goal for the speaker is to 'sound good to his listeners.' Evaluations which involve listener judgments along selected scales, however, require trained judges in order to establish reliability and validity, and such procedures do not relate specific elements of the speech signal to the changes which are perceived. I Approaches which do not require value judgments by listeners also have begun to be employed in studying speech variations in cleft palate (3, '7, 14, 16, 17). Further development of these approaches as indices of speech function in oral cleft patients seems important since they should facilitate: a) the development of measures of speech status which do not require trained judges and b) the identification of specific speech elements by which subjects may be differentiated and the effects of treatment procedures described. The purpose of the present study was to investigate the use of word intelligibility as a measure of the changes in speech which may accom— pany therapy programs for oral cleft patients with palatopharyngeal in-sufficiency and related articulation and resonation disturbances.