Phonological processing and decoding abilities in early elementary school-aged children with speech sound disorders and developmental dyslexia.

Phonological processing and decoding are core foundations of literacy acquisition. Children with speech sound disorders (SSD) often show weaknesses in phonological awareness, memory, and retrieval, which can compromise their ability to decode print into sound. However, outcomes among SSD populations are heterogeneous, particularly when developmental dyslexia (DD) co-occurs. This study examined whether early elementary school-aged children with SSD only, SSD with DD (SSD+DD), and DD exhibit distinct profiles across phonological processing and decoding abilities. Forty-seven school-aged Korean children completed standardized measures of phonological awareness (syllable, phoneme, elision, blending), phonological memory (nonword and sentence repetition, picture-pointing), rapid automatized naming (digits, letters), and decoding (real vs. nonword; consistent vs. inconsistent phoneme-grapheme correspondence). The results showed that the SSD+DD group performed significantly below all other groups in phonological awareness, memory, and retrieval. In decoding, SSD+DD showed markedly reduced accuracy and lacked the typical advantage for real words over nonwords. For phoneme-grapheme correspondence, all groups performed better on consistent than inconsistent items, but SSD+DD remained significantly weaker than the others. Comorbid SSD+DD is associated with broad phonological processing deficits and disproportionate decoding impairment, distinguishing it from SSD only and DD alone. The findings underscore the interdependence between phonological and decoding skills, highlighting the need for integrated assessment to identify children at elevated risk for reading difficulties.