Basics
Deafness (Latin: Surditas) is defined as severe hearing loss or complete deafness. The degree of deafness is differentiated between absolute and practical deafness. Absolute deafness means that the person affected cannot perceive any sounds. In the case of practical deafness, hearing of various sounds and noises is possible, but to too small an extent to understand spoken language.
The loss of hearing does not necessarily have to be due to damage to the peripheral hearing organ (which includes the outer, middle and inner ear). The cause may also be a failure of the cochlear nerves (auditory nerves) or the areas of the brain responsible for hearing, as well as certain psychological disorders.