This application proposes the study of central auditory processing (CAP) in children with communication disorders and in normal children. Categorical perception, auditory capacity determined from dichotic listening and the dichotic "lag" effect will serve as measures of CAP. The results will be used to establish developmental "milestones" for CAP, a classification of impaired CAP, and age-specific tests for these impairments. These studies will allow evaluation of the role of CAP in language acquisition through comparisons of language and language development in children with communication disorders and impaired CAP, children with communication disorders with normal CAP, and normal children. Two sets of children with normal to superior intelligence will be studied: a control set and a set with specific learning disorders or dyslexia.