Types of Hearing Loss
Conductive Hearing Loss
Occurs when sound is not conducted efficiently through the outer and middle ears, including the ear canal, eardrum, and the small bones, or ossicles, of the middle ear. It usually involves a reduction in sound level, or the ability to hear soft sounds. This type can often be corrected through medicine or surgery.
Presence of fluid in the ear associated with colds, allergies, ear infections (otitis media); or a poorly functioning Eustachian tube are common causes of loss of conductive hearing. Other common causes of this hearing impairment include a build-up of wax in the ear canal, perforated eardrum, or damaged or defective ossicles.
Sensorineural Hearing Loss
This is the most common type with more than 90 per cent of all hearing aid wearers having loss of sensorineural hearing. It can occur in one of two ways. The first is when the delicate hearing cells (hair cells) in the inner ear are damaged they become unable to convert sound vibrations into the electrical signals needed by the auditory nerve. Secondly, when nerve pathways in the auditory nerve itself become damaged, the signals are prevented from reaching the brain.
Loss of sensorineural hearing not only involves a reduction in sound level, or ability to hear soft sounds but also affects the ability to hear and understand speech clearly. Although this damage can be caused by exposure to loud noise – through working in a noisy environment for too long – the primary cause in adults is ageing. It is a permanent loss and cannot be corrected medically or surgically.
Mixed Hearing Loss
Sometimes a loss of sensorineural hearing may occur in combination with a loss of conductive hearing. In other words, there may be damage in the outer or middle ear and the inner ear or auditory nerve. If this happens, it is referred to as a mixed hearing loss.
Central Hearing Impairment
Central hearing impairment occurs when auditory centres of the brain are affected by injury, tumour, disease, heredity or unknown causes. Central hearing impairment does not necessarily involve (although it may) hearing impairment. Central hearing impairment involves auditory discrimination, sound localisation, auditory pattern recognition, the temporal aspects of sounds, and the ability to deal with degraded and competing acoustic signals.
If you suspect you may have a hearing loss or other hearing related problem, please come in for an appointment.