Predicting Intelligibility: An Investigation of Speech Sound Accuracy in Childhood Apraxia of Speech

Background: Childhood apraxia of speech (CAS) is a pediatric speech disorder that significantly affects communication and life participation. Most CAS treatment research uses speech accuracy as primary outcome measure, on the assumption that accuracy predicts communicative success. However, this relationship has not yet been examined in this population, limiting our understanding of the impact of available treatments. Purpose: The purpose of this study is to explore the relationship between speech accuracy and intelligibility in children with CAS. Intelligibility is defined here as the proportion of words correctly understood by an unfamiliar listener. Methods: Adult listeners, who were unfamiliar with children with CAS, listened to recordings of children with CAS producing single words, and typed what they heard the child say. Separately, and prior to the listening experiment, the children’s words were scored for accuracy using various measures, including the percent phonemes (sounds) correct (PPC), percent consonants correct (PCC), and percent vowels correct (PVC). The relationship between these accuracy measures and intelligibility were examined descriptively. Results: Preliminary findings suggest that there is a positive relationship between intelligibility and PPC and PCC in children with CAS. Conclusions: Implications of these findings for clinical practice as well as future treatment research are discussed.