Despite the success of cochlear implants, devices surgically placed in the inner ears of patients with severe hearing loss, there remains substantial variability in the overall speech perception outcomes for the children and adults who receive them. The main goals of this project are: i) to improve our understanding of how cochlear implants affect the developing auditory system, ii) apply that knowledge to test new methods for programming children and adults, and iii) to study how long it takes listeners to adapt to new cochlear implant programs over the short- and long-term. The results will improve our understanding of how the deafened auditory system develops with cochlear implant stimulation and advance clinical practice to improve hearing outcomes in cochlear implant listeners.