The ear is the sense organ for hearing. Defects in the ear can result in hearing loss. This loss may be referred to as a hearing impairment or a hearing disability. There are different types of hearing disabilities and their causes vary.
Types of hearing loss
A conductive hearing loss involves defects or obstruction of some part of the external or middle ear. The physical vibrations of sound are no longer transmitted through air, bone, or tissue because of the obstruction or defect. Most problems are medically corrected.
A sensorineural hearing loss results from damage or disorder occurring in the inner ear or of the auditory nerve. A hearing loss of this type is often more difficult, and often impossible to treat medically.
A mixed hearing loss is a combination of more than one type of loss, usually conductive and sensorineural.
A central hearing loss is the inability of the brain to process, recognize or understand sounds or speech accurately.
A non-organic hearing loss, often called a ‘functional loss’, is a result of some sort of psychological cause. There is nothing physically wrong with the person’s hearing mechanism.
Causes of hearing loss
1) The causes of conductive hearing loss include the following.
Malformations of the ear, for example, closure of the outer ear or malformation of the auricle (the part of the ear that we see). Impacted cerumen or ear wax, that is, the cerumen accumulates in the ear canal forming a plug. This partially or completely blocks the canal. Otitis externa, is an inflammation of the wall of the external auditory canal. This may cause a swelling which may block the canal. Polyps are masses of tissue which grow outward from a surface. Polyps causes blockage of the ear canal. Prolapsed canal, associated with the aging process, is a breakdown or sag of the tissue around the ear canal. It causes the walls of the canal to collapse. Perforations or ruptures are holes in the eardrum. They are caused by infection, a foreign object, a bone fracture, or a nearby explosion, or a blow to the ear by the palm of the hand. Otitis media is the presence of fluid in the middle ear. Congenital problems can also cause conductive loss. Fluid drainage, tumors and foreign objects in the ear are also possible causes.
2) The causes of sensorineural loss include the following
Viral infections produce toxins which affect sensitive nerve endings in the inner ear and cause a sensorineural loss. These diseases include measles, influenza, mumps, whooping cough, scarlet fever, meningitis, diphtheria, chicken pox and other such viral illnesses. There are drugs which cause sensorineural loss. These are known as ototoxic drugs and they include quinine, streptomycin, neomycin and kanamycin. These drugs affect the inner ear. Acoustic Trauma also causes sensorineural loss. Acoustic Trauma occurs from a single loud noise or explosion which damages the inner ear. Noise induced trauma is results from long periods of exposure to high noise levels. Sensorineural loss is also caused by Meniere’s disease. This disease affects the entire inner ear.
3) The causes of central hearing loss are:
A tumor or abscess Syphilis Arteriosclerosis Multiple sclerosis Rh incompatibility Brain hemorrhage Strokes Gunshot wounds Skull fractures Lack of oxygen to the brain
4) In non-organic hearing loss individuals are truly convinced that they cannot hear or hear well even when there is nothing physically wrong with their hearing. Emotional stress or tension may be the cause.
The above describes the different types of hearing disabilities and their causes. As discussed, they vary depending on which part of the ear or brain is affected.