(1) Application of cortical auditory evoked potentials (AEPs) and dipole source analysis to characterize and model maturation of sound-evoked cortical activity in normal-hearing humans; (2) investigations of the effects of deafness and cochlear implant use on maturing neurophysiological activity and its relationship to developing auditory behavioral skills including speech and language; (3) development and application of objective single-subject statistics for detecting the mismatch negativity (MMN-an evoked potential that reflects thalamic and cortical processes underlying short-term auditory memory) to investigate changes in auditory discrimination as a function of hearing experience (i.e., maturation, steeply-sloping hearing loss, implant use); (4) co-registration of AEP and fMRI data (including dipole modeling of AEPs) of speech and non-speech evoked cortical activity in normal-hearing and hearing impaired populations.