Speech Inconsistency in Children With Childhood Apraxia of Speech, Language Impairment, and Speech Delay: Depends on the Stimuli

Abstract

Purpose The current research sought to determine (a) if speech inconsistency is a core feature of childhood apraxia of speech (CAS) or if it is driven by comorbid language impairment that affects a large subset of children with CAS and (b) if speech inconsistency is a sensitive and specific diagnostic marker that can differentiate between CAS and speech delay. Method Participants included 48 children ranging between 4;7 to 17;8 (years;months) with CAS ( n = 10), CAS + language impairment ( n = 10), speech delay ( n = 10), language impairment ( n = 9), or typical development ( n = 9). Speech inconsistency was assessed at phonemic and token-to-token levels using a variety of stimuli. Results Children with CAS and CAS + language impairment performed equivalently on all inconsistency assessments. Children with language impairment evidenced high levels of speech inconsistency on the phrase “buy Bobby a puppy.” Token-to-token inconsistency of monosyllabic words and the phrase “buy Bobby a puppy” was sensitive and specific in differentiating children with CAS and speech delay, whereas inconsistency calculated on other stimuli (e.g., multisyllabic words) was less efficacious in differentiating between these disorders. Conclusions Speech inconsistency is a core feature of CAS and is efficacious in differentiating between children with CAS and speech delay; however, sensitivity and specificity are stimuli dependent.