Vowel Accuracy and Segmental Variability Differentiate Children With Developmental Language Disorder in Nonword...

Purpose Poor nonword repetition accuracy is a hallmark of children with developmental language disorder (DLD). However, other diagnostic categories also show impaired nonword repetition performance relative to children with typical development (TD); therefore, this task is currently a sensitive but nonspecific index of DLD. In this study, we investigated segmental and kinematic aspects of nonword repetition performance to further specify the diagnostic utility of nonword repetition tasks (NRTs) in diagnosing DLD. Method Forty children, ages 48-86 months, participated, including children with DLD (n = 12), speech sound disorder (SSD; n = 14), and TD (n = 14). All children completed an assessment battery to determine group classification, a classic NRT (Dollaghan & Campbell, 1998), and an experimental NRT designed to measure segmental and articulatory (specifically lip aperture) variability. We assessed nonword repetition accuracy in the classic and experimental NRTs and segmental and kinematic variability in the experimental NRT. Results In both the classic and experimental NRTs, children with SSD and DLD produced nonwords with lower phoneme and consonant accuracy compared to children with TD. Children with DLD produced more vowel errors compared to children with TD in both tasks. In the experimental NRT, children with DLD produced nonwords with high levels of segmental variability compared to children with TD. Children with SSD did not differ from children with TD or children with DLD in the vowel accuracy or the segmental variability measures. The articulatory variability measure did not reveal any group differences. Conclusions In the presence of speech sound difficulties, low nonword repetition accuracy does not aid in the diagnosis of DLD. However, vowel accuracy and segmental variability appear specific to DLD status in NRTs.