Lip and tongue function in children with developmental speech disorders: A preliminary investigation

Abstract

Four children with developmental verbal dyspraxia (DVD), and three children with inconsistent deviant phonological disorder were compared to age-matched control children on measures of tongue strength and endurance and lip movement. The instrument for measuring tongue strength was composed of an air-filled soft rubber bulb connected to a pressure transducer. Measurements of lip movement during speech and non-speech tasks were taken from a video-recording of the child's mouth, recorded using a Perspex grid overlay. The results indicated that the DVD subjects were poorer than the control children on all measures of tongue strength and endurance. While the inconsistent deviant children performed similarly to age-matched controls on the maximum tongue strength task, their performance on endurance and repetitive tasks fell between that of the DVD and control groups. The preliminary lip movement analysis suggested some deficit in control of lip movement for the DVD and inconsistent subjects. Overall the findings support the hypothesis that children with DVD and those with inconsistent deviant phonology have some form of motor impairment. The differential performance of the two subject groups on tongue strength and endurance tasks is in accordance with the hypothesis that DVD and inconsistent deviant phonology are distinct subgroups of developmental speech disorders. The need for further physiological investigation of the oro-motor skills of speech-impaired children is discussed.