Hearing impairments: causes, effects and rehabilitation

It is almost 150 years since Sir William Wilde (Figure 1), one of the first surgeons to call himself an Otologist, and the father of the celebrated writer, Oscar, considered the causes of deafness in this pessimistic way. The present situation is very different, and in this chapter the causes of hearing impairments and the many strategies that can be utilized to rehabilitate hearing-impaired individuals will be considered. Hearing impairments are normally divided into groups based on the anatomical site of the problem. Thus hearing losses can be subdivided into conductive (outer ear or middle ear), cochlear (inner ear), retrocochlear (auditory nerve) and central (brain) causes. The standard tests of hearing easily distinguish conductive losses from the other types but are less good at distinguishing cochlear, retrocochlear and central auditory problems from each other. The latter three causes are therefore in practice often amalgamated and the classification is simplified to conductive and sensorineural.