As a special surgical procedure, the cochlear implantation should include the following tests in addition to the usual clinical examination before surgery. I. Subjective hearing examination: including pure tone audiometry and behavioral audiometry. 1. Pure tone audiometry: The frequency range of pure tone audiometry is from 125 to 10,000 Hz, and the sound level range is from 0 to 120 decibels, which basically includes the main auditory range of the hearing area of the human ear. The unit is expressed in hearing level (HL) decibels. Pure tone audiometry is commonly used in clinical diagnosis. However, because pure tone audiometry is used to determine the hearing condition through the response of the person being examined, it has the disadvantage of poor objectivity, especially for children, its accuracy is poor, and it cannot be used for testing infants and children. 2.Behavioral audiometry: Behavioral audiometry refers to giving the test subject an acoustic stimulus and observing the behavioral response of the test subject in order to understand his or her hearing level. Including: (1), auditory reflex: applicable to newborns from 0 to 3 months old. (2), auditory behavioral response: applicable to children after 3 months of age. (3), Conditioned orienting reflex: for children from 1 to 3 years old. (4) Play audiometry: applicable to children over 3 years old. II. Objective hearing examination: ABR, otoacoustic emission are commonly used in clinical practice. 1. ABR: i.e. auditory brainstem response, the results of which can reflect whether there are abnormalities in various parts of the auditory pathway (such as the auditory nerve and brainstem nuclei). Contraindications for cochlear implantation include abnormal hearing nerve function, so preoperative ABR examination can clarify whether the patient has high-frequency hearing loss and whether there is a lesion in the auditory nerve at the same time. 2. Otoacoustic emission: to detect the function of cochlear hair cells. Imaging examination: CT and MRI. 1. CT: Preoperative CT of the temporal bone is taken to understand the anatomical structure of the ear, including: cochlear deformity, facial nerve alignment, middle ear morphology, etc. CT of the temporal bone can show the anatomical structure around the patient’s cochlear implant area, which is a guide for the surgery. 2. MRI: i.e. magnetic resonance imaging, which can reflect the morphology of the patient’s cochlear membrane vagus and has certain significance for the diagnosis of large vestibular syndrome.