User:Deaf not dumb/sandbox

Deafness, Deaf not dumb.. or hearing loss is a partial or total inability to hear. Hearing loss exists when there is diminished sensitivity to the sounds normally heard. The term deaf--Deaf not dumb (talk) 06:53, 12 August 2012 (UTC)deaf not dumb File:Example.jpg|Caption2 ]]]]]]]] is usually reserved for people who have relative insensitivity to sound in the speech frequencies. The severity of a hearing loss is categorized according to the increase in volume that above the usual level before the listener can detect it. Deafness

Deafness is defined as the degree poor hearing such that a person is unable to understand speech through hearing even in the presence of amplification. In profound deafness, even the loudest sounds that can be produced by an audiometer (an instrument used to measure hearing) may not be detected. Totally deaf comes next after profoundly deaf, these will have no hearing at all. Speech perception

Another aspect to hearing involves the perceived clarity of a sound rather than its amplitude. In humans, that aspect is usually measured by tests of speech perception. These tests measure one's ability to understand speech, not to merely detect sound. There are very rare types of hearing impairments which affect speech understanding alone. The following are some of the major causes of hearing loss. There is a progressive loss of ability to hear high frequencies with increasing age known as presbycusis. This begins in early adulthood, but does not usually interfere with ability to understand conversation until much later. Although genetically variable it is a normal concomitant of aging and is distinct from hearing losses caused by noise exposure, toxins or disease agents. Noise is the cause of half of all cases of hearing loss, causing some degree of problems in 5% of the population globally.