Hearing, Hardness of

a persistent impairment of hearing that makes it difficult to understand spoken words.

In children, hardness of hearing often results from acute or chronic otitis and from diseases of the nose and nasopharynx, in particular, adenoiditis. Hearing is most severely impaired by diseases of the inner ear and acoustic nerve. Congenital hardness of hearing sometimes occurs; like hardness of hearing originating in early childhood, it may interfere with the development of speech. Hardness of hearing in adults may be caused by otosclerosis, impairment of the blood supply to the inner ear, age-related changes in the acoustic nerve (senile hardness of hearing), prolonged exposure to loud noise, and chronic poisoning by alcohol, nicotine, mercury, or lead.

Three degrees of the disorder are distinguished. With mild hardness of hearing, whispering is heard at a distance of 1–3 m and conversational speech at more than 4 m. With moderate hardness of hearing, whispering can be heard at less than 1 m and conversational speech at 2–4 m. With severe hardness of hearing, whispering cannot be heard even close to the ear, and conversational speech is perceived at less than 2 m.

In the hard of hearing, the ear generally manifests permanent changes. However, hearing can be improved in some cases by conservative therapy or by surgery. Hearing aids and training in lip reading are very helpful.