New Zealand Association of Independent Audiologists
Types of Hearing Loss
There are two basic types of hearing loss, ones called CONDUCTIVE losses and ones known as SENSORI-NEURAL losses.
CONDUCTIVE LOSSES
Conductive losses are ones which occur in the outer and middle ear and interfere with the sound being conducted' to the inner ear. Blockage of the outer ear can cause loss of hearing. A common problem in the outer ear canal is the build up of wax. Wax, called cerumen' (pronounced "sir-roo-men") is secreted in the outer ear. It is sticky (to catch airborne particle such as dust), slightly germicidal (to kill, or at least damage, germs) and has an unpleasant odor (which is why most bugs which fly by the ear don't go in). Normally it dries into particles that fall from the ear. In some persons, however, the cerumen glands are very active, producing more than is needed. If not cleaned regularly, the wax can accumulate and eventually block sound from reaching the ear drum. This type of problem is easily corrected by removing the wax. There are eardrops available at pharmacies to help soften dry wax. This is recommended, because the removal of wax by a professional, while safe, can be very painful if the wax is too hard.
Another conductive loss is when there is a disruption of the eardrum or bones of the middle ear. The middle ear results in a mechanical advantage which helps sound coming through the air cause the fluid in the inner ear to move. Any malfunction of the middle ear can cause a hearing loss. The most common middle ear problem results from a build up of fluid in the middle ear. Fluid is secreted by cells in the middle ear teo lubricate the mechanism. As fluid builds up, it is drained by opening the Eustachian tube, a tube which opens to the throat. The Eustachian tube is normally opened by activities such as swallowing, yawning, and chewing. An inflammation of the tube may keep it closed, and thus fluid builds in the middle ear. This is usually a problem that can be corrected. It is often the result of an upper respiratory infection and can be cleared with treatment.
SENSORI-NEURAL LOSSES
Sensori-neural losses are losses that occur because of damage to the inner ear or the neural pathways from the inner ear to the brain. Damage to the inner ear is called sensory hearing loss and can be caused by many things. It can be the result of trauma, such as a head injury. It can occur as a result of an infection that reaches the inner ear. The inner ear can be damaged by excessive noise, one of the more common causes. The inner ear normally deteriorates with age, so almost everyone past the age of 65 will experience some sensory hearing loss. There is usually no medical treatment which can restore the inner ear. A well fitted hearing aid is often of significant benefit to people with sensory hearing losses
Hearing loss can also be the result of damage to the nervous system through which neural impulses generated by the inner ear pass on their way to the brain . The most common cause of this type of loss is a tumor (usually benign) which pinches the nerve. These tumour usually require surgical treatment and patients are more often left with much reduced or no hearing in the effected ear. Hearing losses that result from such neural problems are not always as easy to help with hearing aids. Fortunately they are also less common.