The inability to perceive sounds. There are two major forms: (a) conductive deafness and (b) perceptive deafness.
The fact of being unable to hear in circumstances where most people would.
partial or complete loss of hearing in one or both ears, caused by the absence or incomplete development of the ear, the auditory nerve, or parts of the brain, by damage to the hearing apparatus (e.g., from infection or injury); or by degeneration (from aging) of the hearing apparatus. In assessing deafness, the degree of hearing loss, the types of sounds that can be discriminated, and the cause of the impairment generally classified as conductive hearing loss or sensorineural hearing loss are determined; treatment depends on these findings and may involve the use of a hearing aid.
An inability to hear, which may affect any age group, with consequences ranging from minor to severe. A small proportion of hearing-impaired persons in the United States are considered profoundly deaf, meaning their hearing loss is so severe they cannot benefit from hearing aids or other forms of mechanical sound amplification. A much larger proportion of people who are hearing impaired can benefit, in varying degrees, from the use of amplification devices.