1. There is no strict age limit for the selection of hearing aids. Children with hearing impairment should be given hearing aids as early as possible to facilitate speech articulation and speech learning.2. Hearing loss of 35-110dB can be equipped with hearing aids. Hearing loss degree of 35 ~ 90dB when the effect is better. Hearing loss of more than 90dB when the effect is poor, but can eliminate the patient’s sense of isolation, increase the sense of security, and can improve the ability to read.3, hearing fluctuations have been stabilized for more than 3 months of sensorineural deafness, such as sudden deafness, traumatic deafness, acoustic injury deafness, toxic deafness, etc., before considering optional hearing aids.4, hearing loss of 40 ~ 60dB between the conductive deafness or mixed deafness, optional hearing aids Chronic suppurative otitis media patients, the condition is stabilized for more than 3 months, can be equipped with hearing aids. 6, the loss of hearing in both ears, can be selected at the same time with two hearing aids. Binaural hearing, favorable sound source localization, as well as binaural noise suppression and other advantages. Thus, wearing hearing aids in both ears has the advantages of improving speech clarity, sound quality, sound localization ability, etc. 7, there are obvious congenital deformities or traumatic deformities should not be selected to match. 8, there are people with vertigo should not be selected to match. 9, the hearing aids are not suitable for those who have a hearing loss. 10, the hearing aids are not suitable for those who have a hearing loss.