We use behavioral (psychoacoustic) tests to measure auditory perception in infants, toddlers, children and adults with normal hearing as well as those who use cochlear implants. Performance on these tests is compared to performance on auditory speech and language measures. We are interested in how spoken language development over time is related to auditory perception. The long term goal is to develop a set of clinically valid auditory tests to measure how well a cochlear implant works for an individual infant. This will enable audiologists and speech pathologists to intervene early for children who are not receiving optimal benefit from their cochlear implant.