ReviewGetting a decent (but sparse) signal to the brain for users of cochlear implants

- The challenge in representing sound with cochlear implants (CIs) is described.
- A breakthrough in 1989 enabled most CI users to understand speech with the CI only.
- Stimulation in addition to that provided by a unilateral CI can be beneficial.
- Further gains in performance are possible and are being pursued.

The challenge in getting a decent signal to the brain for users of cochlear implants (CIs) is described. A breakthrough occurred in 1989 that later enabled most users to understand conversational speech with their restored hearing alone. Subsequent developments included stimulation in addition to that provided with a unilateral CI, either with electrical stimulation on both sides or with acoustic stimulation in combination with a unilateral CI, the latter for persons with residual hearing at low frequencies in either or both ears. Both types of adjunctive stimulation produced further improvements in performance for substantial fractions of patients. Today, the CI and related hearing prostheses are the standard of care for profoundly deaf persons and ever-increasing indications are now allowing persons with less severe losses to benefit from these marvelous technologies. The steps in achieving the present levels of performance are traced, and some possibilities for further improvements are mentioned.This article is part of a Special Issue entitled .