As has often been said, it is the brain that hears, not the ear. Indeed, brain plasticity accounts for much of the success of the cochlear implant (CI). In postlingually deaf CI users, the coarse spectro-temporal patterns provided by the CI are often sufficient to activate central auditory speech templates developed during previous acoustic hearing (AH). Prelingually deaf CI users are able to develop these central auditory templates with the CI alone. Current CI candidacy allows for increasing amounts of AH in the implanted and/or non-implanted ears which can greatly improve CI users’ access to pitch information, important for challenging listening conditions such as prosody perception, music perception, talker identification, and segregation of competing speech. Again, brain plasticity plays a strong role in combining acoustic and electric stimulation patterns. In all these scenarios, CI users will “passively” adapt to these new stimulation patterns during the first 6–12 months of implant use. However, passive adaptation is often incomplete. For CI users with available AH, the more familiar acoustic stimulation patterns may limit adaptation to new electric stimulation patterns. “Active” auditory training has been shown to significantly improve CI users’ speech and music perception, even with extensive experience with their device. Given the limited access to clinical auditory rehabilitation, computer-based auditory training has benefitted many CI users. As CI technology continues to improve and AH plays a more substantial role in CI users, auditory training remains an important component of successful CI outcomes, especially when challenging listening conditions are considered.