The Repeated Pronunciation of Plosives by a Cleft Palate Patient and Normal Controls : A Clinical Study to Design the Proper Prosthesis

This study was undertaken to establish a method for evaluating speech disorders by determining the constancy of articulatory activity during the repeated pronunciation of plosives. Tested and compared were the speech patterns of 10 normal controls and one cleft palate patient tested at different stages, i.e., before prosthetic treatment (stage A), while wearing a temporary overdenture (stage B), at insertion of the final prosthesis (stage C) , and at six months after insertion of the final prosthesis (stage D). All tested subjects were instructed to repeatedly pronounce /pa/ , /ta/, /ka/ and /pataka/ as rapidly as possible until running out of breath. These vocal patterns then were analyzed by a sound spectrograph (DSP Sona-Graph, Model 5500, Kay Co. USA) and studied on an expanded time-wave CRT display to measure three items : the characteristics of the spectrographic pattern, the number of the repetitions, and the duration of the sound. The duration of the consonants and vowels were measured, as well as the intervals between each syllable . Further, each consonant was divided into two parts : the duration of the plosive spike , and the damping of this spike to the beginning of the next sound. Results revealed that the sound patterns of the cleft palate subject during stage A varied greatly from those of the normal subjects, but that these differences gradually diminished during stages B and C and became remarkably similar at stage D , almost resembling the patterns of the normal controls. While the number of repetitions that the cleft palate patient was capable of was limited during stage A, the ability to repeat plosives increased as the prosthetic treatment progressed . Similarly, the duration of the consonant and the plosive spike of the /k/ of the patient at stage A was much longer than that of the controls, but this difference also decreased . Based on the results of this study, it was concluded that to improve the speaking capability of cleft palate patients, the designed dental prosthesis must not only achieve naso-pharyngeal or naso-oral closure but also must include a compatible occlusal vertical dimension and a proper maxillary dental arch.