Cochlear implants are an important treatment for profound deafness and have helped hundreds of thousands of deaf people around the world emerge from a world of silence. But which deaf patients are suitable for cochlear implants? When is the best time to receive this treatment? Here, Dr. Hongzheng Zhang will introduce you to this knowledge. The cochlear implant system converts everyday sound information into encoded electrical impulses. These electrical impulses stimulate the auditory nerve fibers in the cochlea, which pick up the electrical signals and send them to the brain, which translates them into sound. This helps people who are deaf to hear. The Cochlear Implant Guidelines state that cochlear implants are primarily used to treat severe or profound sensorineural deafness in both ears. The criteria for cochlear implantation in patients with prespeech deafness who have been deaf since before they learned to speak are: 1. The age is usually 12 months to 6 years. The younger the age of the implant, the better the results. Children or adolescents over 6 years of age need to have a certain hearing and speech foundation, a history of hearing aid wear and auditory-verbal rehabilitation since childhood. 2. Severe or very severe sensorineural deafness in both ears. After comprehensive audiological evaluation, children with severe deafness whose hearing threshold exceeds 70 dB should have cochlear implantation if the hearing aid is ineffective or unsatisfactory for 3-6 months; children with very severe deafness whose hearing threshold exceeds 90 dB can be considered for cochlear implantation. 3. No contraindication to surgery. 4. The guardian and/or the implant recipient has a correct understanding of cochlear implantation and appropriate expectations. 5. The patient is eligible for auditory-speech rehabilitation education. For patients with postlingual deafness who can already speak, the criteria for selecting a cochlear implant are as follows: 1. Patients of all ages with postlingual deafness 2. Severe or profound sensorineural deafness in both ears and inability to communicate normally in auditory speech with hearing aids. 3. No contraindication to surgery. 4. The implant recipient and/or guardian has a correct understanding of cochlear implantation and appropriate expectations. What are the contraindications to cochlear implantation? 1. Absolute contraindications: severe malformations of the inner ear, such as Michel malformation and other undeveloped cochlea; absence or interruption of the auditory nerve; acute purulent inflammation of the middle ear mastoid. 2. Relative contraindications: frequent seizures that cannot be controlled; severe mental, intellectual, behavioral and psychological disorders, and inability to cooperate with auditory-verbal training.