Comparing the Informativeness of Single-Word Samples and Connected Speech Samples in Assessing Speech Sound Disorders

Purpose Speech-language pathologists (SLPs) are faced with the challenge of quickly and accurately identifying children who present with speech sound disorders (SSD) compared to typically developing (TD) children. The goal of this study was to compare the clinical relevance of two speech sampling methods (single-word vs. connected speech samples) in how sensitive they are in detecting atypical speech sound development in children, and to know whether the information obtained from single-word samples is representative enough of children's overall speech sound performance. Method We compared the speech sound performance of 37 preschool children with SSD (M _age = 4;11 years) and 37 age-sex-matched typically developing children (M _age = 5;0 years) by eliciting their speech in two ways: (a) a picture-naming task to elicit single words, and (b) a story-retelling task to elicit connected speech. Four speech measures were compared across sample type (single words vs. connected speech) and across groups (SSD vs. TD): intelligibility, speech accuracy, phonemic inventory, and phonological patterns. Results Interaction effects were found between sample type and group on several speech sound performance measures. Single-word speech samples were found to differentiate the SSD group from the TD group, and were more sensitive than connected speech samples across various measures. The effect size of single-word samples was consistently higher than connected speech samples for three measures: intelligibility, speech accuracy, and phonemic inventory. The gap in sample type informativeness may be attributed to salience and avoidance effects, given that children tend to avoid producing unfamiliar phonemes in connected speech. The number of phonological patterns produced was the only measure that revealed no gap between two sampling types for both groups. Conclusions On measures of intelligibility, speech accuracy, and phonemic inventory, obtaining a single-word sample proved to be a more informative method of differentiating children with SSD from TD children than connected speech samples. This finding may guide SLPs in their choice of sampling type when they are under time pressure. We discuss how children's performance on the connected speech sample may be biased by salience and avoidance effects and/or task design, and may, therefore, not necessarily reveal a poorer performance than single-word samples, particularly in intelligibility, speech accuracy, and the number of phonological patterns, if these task limitations are circumvented. Our findings show that the performance gap, typically observed between the two sampling types, largely depends on which performance measures are evaluated with the speech sample. Our study is the first to address sampling type differences in SSD versus TD children and has significant clinical implications for SLPs looking for sampling types and measures that reliably identify SSD in preschool-aged children.