A hearing aid is a device designed to improve hearing levels by making sound audible to a person with hearing loss. Hearing aids are used for a variety of auditory system pathologies including sensorineural hearing loss and conductive hearing loss. Hearing aid candidacy is typically determined by an audiologist, who will also fit the device according to the nature and degree of the hearing loss being managed.

The amount of benefit experienced by the hearing aid user is depending on the severity, type, and etiology of the hearing loss, and also on the personality, motivation, and lifestyle of the device user.