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

Sensorineural hearing loss

Sensorineural hearing loss can be acquired or congenital and is caused by damage to, or malfunction of the cochlea (sensory part) and the hearing nerve (neural part). Sensorineural hearing loss leads to a loss of loudness as well as a lack of clarity. This type of loss is almost always permanent in nature and can usually be helped by hearing aids. The potential benefits/limitations of hearing aids can be predicted to some extent based on specific test results obtained on the hearing test.

Causes of sensorineural hearing loss include:

  • the aging process
  • excessive noise exposure
  • diseases such as meningitis and Meniere's disease
  • viruses such as mumps and measles
  • medications or treatments which are toxic to hearing
  • head injuries
  • tumours or growths by the auditory nerve
  • genetic predisposition
  • congenital
  • premature birth or other birth trauma
  • jaundice

Conductive hearing loss

This type of hearing loss can be acquired or congenital and is caused by a blockage or damage in the outer and/or middle ear. A conductive hearing loss leads to a loss of loudness rather than speech clarity and can often be treated medically or surgically.

Some of the causes of conductive hearing loss are:

  • blockages of the ear canal by impacted wax or foreign objects
  • outer ear infection (sometimes due to swimming)
  • middle ear infection (common in children)
  • perforated eardrum
  • otosclerosis (a hereditary condition where abnormal bone grows around a portion of the middle ear bones)
  • partial of complete closure of the ear canal

Mixed hearing loss

Mixed hearing loss results when there is a problem in both the conductive pathway (outer and/or middle ear) as well as in the nerve pathway (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 a history of excessive noise exposure.