1.Definition of hearing disability Hearing disability refers to the permanent hearing impairment in both ears of varying degrees due to various reasons, so that people cannot hear or cannot hear the sounds of the surrounding environment and speech, which affects daily life and social participation. 2.Hearing disability classification Hearing disability level I: hearing system structure and function of extremely severe damage, the better ear average hearing loss ≥ 91dBHL, without the help of hearing devices, can not rely on hearing for speech communication, in understanding and communication and other activities are extremely limited, in the participation of social life there are very serious obstacles. Hearing Disability Level 2: Severe impairment of the structure and function of the auditory system, average hearing loss in the better ear between 81-90 dBHL, severe limitations in understanding and communicating without the help of hearing aids, and severe impairment in participating in social life. Hearing Disability Level 3: Moderately severe impairment of the structure and function of the auditory system, with an average hearing loss in the better ear of 61-80 dBHL, moderate limitations in understanding and communication activities without the aid of hearing devices, and moderate impairment in participation in social life. Hearing Disability Level 4: Moderate impairment of the structure and function of the auditory system, average hearing loss in the better ear between 41-60 dBHL, mild limitation in understanding and communication activities without the help of hearing aids, and mild impairment in participating in social life.