A cochlear implant (CI) is a sophisticated neural prosthesis designed to bypass damaged or non-functional hair cells in the inner ear (cochlea) and provide direct electrical stimulation to the auditory nerve. Unlike traditional hearing aids, which amplify sound, a CI converts acoustic signals into a coded stream of electrical pulses. This process begins at the external speech processor, where microphones capture sound and a digital signal processor (DSP) analyzes the frequency, intensity, and timing of the audio.

The encoded signal is then transmitted across the skin via an induction coil to the internal receiver-stimulator. This internal unit triggers an electrode array, which is surgically inserted into the scala tympani of the cochlea. For a detailed breakdown of the electrode configurations and signal-processing strategies used in modern devices, the Cochlear Implants Market overview provides a technical analysis of current hardware. By stimulating specific regions of the auditory nerve corresponding to different frequencies (tonotopicity), the device allows the brain to perceive "sound" even in cases of profound sensorineural hearing loss.

The success of transduction relies heavily on "mapping" or "programming" the device. Audiologists must determine the Threshold (T-level) and Comfort (C-level) for each individual electrode to ensure the electrical current is high enough to be perceived but low enough to remain comfortable. As neuroplasticity occurs, the brain learns to interpret these new electrical signals as meaningful speech, a process that can take months of intensive auditory rehabilitation.