Cochlear implantation is a corrective treatment for people who suffer from severe or profound deafness by using a cochlear implant, a replacement device for the inner ear, to bring their hearing close to normal and train them to communicate verbally. This is an internationally recognized high technology in the medical field. So, what exactly is a cochlear implant? A cochlear implant is an electronic device that replaces the function of the human ear and helps restore or provide the sense of hearing to adults and children who are severely or profoundly deaf. The cochlear implant is composed of an in vivo part, which consists of implanted electrodes and a receiver/stimulator, and an in vitro part, which consists of a speech processor, a directional microphone and a transmission device. The sound is received by the directional microphone and converted into an electrical signal, which is then transmitted to the speech processor where the signal is amplified and filtered, and transmitted by the transmitter to the receiver/stimulator where the electrical impulses are sent to the corresponding electrodes, thereby stimulating the excitation of the auditory nerve fibers and transmitting the sound information to the brain to produce hearing. The in-the-ear portion of the cochlear implant is surgically implanted between the muscles of the head and the temporal bone. Prior to the surgery, the patient is given a thorough audiological, medical and psychological evaluation and given the necessary preoperative hearing rehabilitation training. The audiological evaluation focuses on the nature, extent and cause of the patient’s deafness and includes subjective and objective audiological examinations. The medical evaluation, on the other hand, includes an otologic and general examination, CT and MRI to understand the middle and inner ear, and an assessment of the patient’s suitability for general anesthesia and the presence of other factors limiting surgery. The preoperative preparation also includes preoperative hearing aids and the necessary aural rehabilitation training to enable the patient to respond to sound, which will be of great help in postoperative adjustment and rehabilitation. The surgery usually takes 1-2 hours. Post-operative wound healing takes 7-10 days. One month after the wound heals, the patient returns to the hospital to be fitted and adjusted to the external equipment. Specialists and audiologists will activate the computer program in the speech processor and adjust the program in the speech processor according to the patient’s comfort level with the sound, so that the patient can hear the sound more comfortably and better. The patient needs to come to the hospital periodically to have the speech processor tuned as the patient needs a period of adjustment to the sounds they hear after the implant. At the same time, the patient has to undergo hearing and speech rehabilitation. For post-speech deaf patients, the training usually takes a few months, while for pre-speech deaf patients, it takes 2-3 years of rehabilitation to achieve more satisfactory results. Currently, more than 100,000 people worldwide have been implanted with different types of cochlear implants. Cochlear implants can help people with severe or profound deafness use their hearing to better communicate with others, thereby allowing them to have more educational and employment opportunities and to return to mainstream society.