Temporal auditory and visual motion processing of children diagnosed with auditory processing disorder and dyslexia

Objective: Auditory processing disorder (APD) is diagnosed on the basis of listening difficulties despite normal audiogram, although the cause is unknown. This study examined the hypothesis that the underlying cause of APD is a modality-specific deficit in auditory temporal processing and also considered how far the auditory impairments in APD differ from those in children with dyslexia. Design: Performance of children diagnosed with APD (N = 22) was compared with that of a normative group (N = 98) as well as with children with dyslexia (N = 19) on a battery of temporal auditory tasks; 2-Hz frequency modulation (FM), 40-Hz FM, and iterated rippled noise detection as well as a control task (240-Hz FM), which is thought to draw on peripheral spectral mechanisms. Visual tasks were coherent form and coherent motion detection. Results: On average, the APD group performed more poorly than the normative group on the 40-Hz FM, 240-Hz FM, and iterated rippled noise tasks. There were no significant differences between the APD and dyslexia group's performance and no evidence for a specific temporal auditory impairment. A higher proportion of children in the APD group performed poorly (