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Slow cortical oscillations play a crucial role in processing the speech envelope, which is perceived atypically by children with Developmental Language Disorder (DLD) and developmental dyslexia. Here we use electroencephalography (EEG) and natural speech listening paradigms to identify neural processing patterns that characterize dyslexic versus DLD children. Using a story listening paradigm, we show that atypical power dynamics and phase-amplitude coupling between delta and theta oscillations characterize dyslexic and DLD children groups, respectively. We further identify EEG common spatial patterns (CSP) during speech listening across delta, theta and beta oscillations describing dyslexic versus DLD children. A linear classifier using four delta-band CSP variables predicted dyslexia status (0.77 AUC). Crucially, these spatial patterns also identified children with dyslexia in a rhythmic syllable task EEG, suggesting a core developmental deficit in neural processing of speech rhythm. These findings suggest that there are distinct atypical neurocognitive mechanisms underlying dyslexia and DLD.

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Cross-language data show that children with dyslexia are poor at recognizing syllable stress patterns, yet their speech production appears normal, suggesting an unexpected disconnect between speech input and output processes. Here we utilized a novel computerized speech copying task based on the speech amplitude envelope (AE) to investigate this disconnect. Seventy-five children with and without dyslexia copied familiar spoken targets like "Aladdin". Children with dyslexia were significantly worse at producing the multi-syllabic targets as indexed by two similarity metrics for computing the AE. They did not differ from other children in producing the pitch contours of items. Accordingly, impaired AE perception in dyslexia is matched by impaired AE production. Children with dyslexia are heard to produce multi-syllabic words normally because their pitch contours are intact.