TYPES OF HEARING LOSS

There are four types of hearing loss: conductive, sensorineural, mixed and central.

›› CONDUCTIVE HEARING LOSS leads to a loss of loudness and can often be corrected by medical or surgical treatment. Possible causes of conductive hearing losses are:

• Blockages of the ear canal by impacted wax or foreign objects.

• An outer ear infection (often due to swimming).

• “Glue ear” (also called middleear infection), most common in young children.

• A perforated eardrum, due to a bad middle-ear infection or a trauma.

• Otosclerosis, a hereditary condition where the bone grows around the tiny stirrup bones in the middle ear.

• Partial or complete closure of the ear canal.

›› SENSORINEURAL HEARING LOSS can be acquired or congenital and is caused by damage to, or malfunction of, the cochlea (sensory part) or the hearing nerve (neural part). This kind of hearing loss leads to a loss of loudness as well as a lack of clarity. Quantity as well as quality of sound is affected, and this may sometimes limit the benefit of a hearing aid. The causes of acquired sensorineural hearing loss include:

• Noise exposure.

• Diseases such as meningitis.

• Viruses, such as mumps and measles.

• Drugs that can damage the hearing system.

• Trauma to the head.

›› MIXED HEARING LOSS results when there is a problem in both the conductive pathway (in the outer or middle ear) and in the nerve pathway (the inner ear). An example of a mixed hearing loss is a conductive loss due to a middle-ear infection combined with a sensorineural loss due to damage associated with the ageing process.

›› CENTRAL HEARING LOSS results from damage to the auditory nerve itself, or the brain pathways that lead to the nerve. Central hearing loss is very rare in babies and children. Possible causes of central hearing loss include:

• Diseases that affect the protective coating around nerve cells.

• Tumours. ●