In infancy, it is necessary to hear the sounds around the child before the child can imitate the sounds and babble. For children who lose their hearing before they are exposed to sound, they often also lose their ability to express themselves verbally, and therefore, such children become deaf and mute, which is typical of prelingual deafness. After such a child is fitted with a cochlear implant, there is a corresponding acoustic signal transmitted, but since the child has never been exposed to sound, he or she may not respond to the acoustic signal generated by the cochlear implant. However, as the child’s hearing and speech skills gradually develop, normal hearing and speech skills can gradually develop with the help of the cochlear implant. However, the time and difficulty of rehabilitation of children with prelingual deafness after cochlear implantation is closely related to the age at which the cochlear implant is installed. 1-3 years old is the peak of language development in young children, and the younger the age at which the cochlear implant is installed, the better the functional rehabilitation. For example, before the age of 1, children are just beginning to babble at this time. If the cochlear implant is implanted at this time and the child can start babbling like a normal child of the same age, then the time to recover is not much different from that of a normal child, or even no different. If the cochlear implant is placed at a later age, such as 3-5 years old, the child has already missed the best period of language development, and normal children of the same age have already learned to speak, so it will take longer for the patient to regain speech and the recovery will be more difficult. Therefore, the younger the age of implantation, the shorter the time of deafness and the less difficult the recovery. Conversely, the older the age of implantation, the longer the time of deafness and the more difficult the recovery. This means that the best age for cochlear implantation is about 1 year old, and the minimum age for cochlear implantation in the ENT department of Friendship Hospital is 6 months old. In short, a child between the ages of half and one year and weighing eight kilograms or more can be considered for cochlear implantation. For patients with post-lingual deafness, that is, adults or children who can already speak before the onset of the disease and can produce normal responses to sound. After the cochlear implant is installed, when the machine starts working, the sounds that the patient hears through the cochlear implant may be different from normal hearing, so after the cochlear implant, there is a familiarization and learning process for the cochlear implant sounds, so that the patient can gradually understand the language and then learn to speak. After the necessary training and familiarization process, most implant recipients can understand the speech of others and participate in everyday conversations.