Naive Listener Ratings of Speech Intelligibility over the Course of Motor-Based Intervention in Children with Childhood Apraxia of Speech

Purpose: The aim of this study was to describe changes in speech intelligibility and interrater and intrarater reliability of naive listeners' ratings of words produced by young children diagnosed with childhood apraxia of speech (CAS) over a period of motor-based intervention (dynamic temporal and tactile cueing [DTTC]). Method: A total of 120 naive listeners (i.e., listeners without experience listening to children with speech and/or language impairments; age range: 18--45 years) orthographically transcribed single-word productions by five children (age range: 2;6-3;11 [years;months]) across three time points over an intervention period (baseline, post-treatment, maintenance). Changes in intelligibility and interrater and intrarater reliability were examined within and across time points. Results: Speech intelligibility significantly increased in children with CAS over the course of treatment, and these gains were also maintained at 6 weeks posttreatment. There was poor-to-fair consistency "between" listeners (interrater reliability) and excellent consistency within listeners (intrarater reliability) in ratings of speech intelligibility within and across time points. Conclusions: Motor-based intervention increases speech intelligibility following a period of DTTC treatment. Variability among naive listeners of speech intelligibility was also present, with intrarater reliability (within listeners) yielding greater consistency than interrater reliability (between listeners). The implications for including naive listeners as raters of speech intelligibility for research and clinical purposes are discussed.