[Causes and assessment of hearing impairment]

Hearing loss is a very common disorder. It is discussed, using the aid of a topical classification. An introductory description of new basic knowledge about the peripheral hearing organ is given first. Such knowledge has had an important influence on the understanding and the evaluation of hearing loss. The diagnosis of conductive hearing loss is relatively easy to make. It represents mainly a quantitative disorder without much loss of qualitative information, and it can often be improved surgically. Conversely, sensorineural hearing loss is always associated with a loss in the quality of the acoustic information. Its most common causes are functional disturbances of the cochlea. The mechanical elements within the cochlea seem to be particularly vulnerable. The differentiation between a cochlear and a retrocochlear hearing loss can be made with confidence using modern audiological tests. This differentiation is particularly important for the early diagnosis of acoustic tumors.