Inner Ear

Hearing Loss

Conductive Loss

When something prevents the sound wave vibrations entering the inner ear it is called a conductive loss – the sound wave conduction is hindered. Generally this type of hearing loss is medically correctable

Causes:

  • wax occluding the ear canal
  • foreign body occluding the ear canal
  • birth defects such as atresia
  • infections where the debris or swelling blocks the ear canal
  • middle ear infections that block the middle ear
  • perforations in the eardrum
  • disruption of the hearing bones

Sensorineural Loss

When the hearing cells in the cochlea cannot pick up or transmit information to the brain it is called a sensorineural loss. This type of hearing loss is most often permanent. Some causes are listed below:

Congenital

  • inherited
  • maternal contact with rubella during pregnancy
  • abuse of drugs during pregnancy that has effected the developing baby

Acquired

  • lack of oxygen in a newborn baby
  • jaundice increases the risk of hearing impairment
  • high fever illness
  • head injuries
  • some medications damage the cochlea
  • the aging process
  • exposure to loud noise

Mixed Hearing Loss

This results when there is a combination of conductive and sensorineural hearing loss present.

Presbycusis

Is hearing loss due to the ageing process. A progressive loss of the inner ear hearing cells – perhaps 2% each year? It effects the high frequency noises first (a ‘ski-slope’ audiogram) becoming noticeable around age 60-65. It begins very slowly and can vary from mild to severe. Onset age and degree of loss vary a great deal.

Speech discrimination is often worse than would be expected from the degree of loss. This is because of ‘recruitment’ – the threshold of hearing and the uncomfortable level of sound are abnormally close. Hence you may hear “speak up I can’t hear you …… don’t shout so loud!” Discrimination may also be effected, “I can hear you but I can’t hear what you are saying”. shouting makes the problem worse. Often folk with presbycusis will use the phrase ” their speech is muffled” when talking about the grandchildren, TV characters, meeting group participants etc.