Cochlear implants are expensive mainly because they are electronic biological products involving complex conversion of sound signals into electrical signals, which are characterized by high human compatibility, precise structure and complex principle. 1. High human compatibility: The cochlear implant electrode is surgically implanted into the inner ear to replace the severely damaged hair cells of the inner ear to feel the sound, and the cochlea of the patient receives the electrical signals through processing and conversion of external sound signals, and the cochlea of the patient receives the electrical signals, and the cochlea’s residual auditory nerves are stimulated subsequently to rebuild the hearing system, which are all relying on the good human compatibility. 2. Precise structure: cochlear implant consists of two parts: in vivo and out of vivo. The in-vivo part includes receiver, stimulator, electrode; the out-of-vivo part includes microphone, speech processor and transmission coil. 3. Complex principle: the electrical signals converted by the speech processor are received and decoded by the receiver in the body through the transmission coil in the form of radio waves across the skin; the electrodes embedded in the cochlea receive the decoded electrical signals; they stimulate the ganglion cells to generate action potentials, and then go through the central end of the auditory nerve to the cochlear nucleus of the brainstem, and then finally the auditory cortex produces hearing. Patients need to wear cochlear implants, please go to a regular hospital for examination and treatment, choose the right cochlear implant to avoid delay.