A loss of hearing occurs when there is impedance to the passage of sound waves to the brain. Hearing loss is different to deafness, in that the latter usually results from a significant illness around the time of birth. There are 3 types of hearing loss (i) conductive (ii) sensorineural (iii) central. Conductive hearing loss happens when sound is prevented from reaching the inner ear, by a defect in the external or middle ear. Sensorineural hearing loss results from damage to structures such as nerves or hair cells, within the inner ear. Hair cells convert sound waves to signals for nervous transmission to the brain, and since they cannot be repaired, the resultant hearing loss is permanent. Central hearing loss is very rare and usually only occurs if there is severe brain damage. Recurrent ear infections can result from exposure to fungi (e.g. in swimming pools). Tinnitus is a constant buzzing or hissing noise in your ear. The sound is believed to originate in the brain, as a mechanism for compensating for damage to the ear.
Cause of conductive hearing loss: middle ear infection, build up of earwax, inflammation and perforation of the eardrum.
Cause of sensorineural hearing loss: drugs (e.g. antibiotics, non-steroidal anti-inflammatory drugs) and infection of the inner ear. Contributing factors: genetics, aging and long term exposure to loud noises.
Risk factors for hearing loss in infancy: recurrent ear infections (otitis media), family history of hearing loss, heredity, congenital abnormalities of the ears, nose or throat, maternal exposure to rubella or syphilis or to ototoxic drugs.
Symptoms in infancy: failure to startle at loud noises, ability to sleep through loud noises, failure to babble, more responsive to loud noises than speech. Symptoms in toddlers: failure to speak by age 2, habitual yelling, showing no interest in being read to, greater responsiveness to facial expressions, shyness, withdrawal and frequent confusion.
Symptoms in adults: Inattentiveness, unusually loud speech, irrelevant comments, in appropriate responses to questions, unusual voice quality and repeated requests to repeat statements.
Who to consult: Dietician, GP, naturopath, otologist.
