Definition and causes
Hearing impairment is a sign that there has been damage to one or more parts of the ear. With age will be hearing generally worse, but there are also a number of diseases that may cause bad hearing. It divides hearing impairment in two types depending on where there has been damage.
Konduktivt hearing loss:
Here's the problem lies in the lydledende part of the ear, so that the sound is not managed so well into the inner ear. This may, for example. caused a jam of ørevoks, blown drum skin or destruction of the small øreknogler or their compounds, for example. seen by otosklerose (see also the ears structure and function). A konduktivt hearing loss can be up to 60dB.
Sensorineural or perceptiv hearing impairments:
Here, there has been damage to the inner ear or hearing nerve. In the inner ear are the snail, which sound waves are converted into a nerve signal that is sent via hearing nerve to the brain. When damage to these structures is the ability to perceive the sounds created or destroyed. There can be seen here total deafness.
Depending on the reason for the reduced hearing may be caused symptoms in the form of tinnitus and dizziness.
Study of hearing
There are a number of studies and tests that can detect the size and type of hearing impairments:
This is a study in which the doctor looks into the drum through the ear canal. There might be. Enlarge or used a special microscope, so the doctor can more easily see the small details. The study may say something about whether the ear drum is intact, if there is fluid in the middle ear (as in middle) or negative pressure in the middle ear (which by inflammation of the eustachiiske pipes).
Voice Fork Test:
There are two types of voting fork testRinneandWeber. By Rinnes sample turned a fork an vote, after which it alternately held off the ear and placed in the bone behind the ear. The patient must now specify where the sound is heard best. If the sound is heard best when the tuning fork placed on the bone, this points to a konduktivt hearing loss. The sound should best be managed through the air, but at a konduktivt hearing loss, heard fluctuations better through bone.
By Weber test placed a fork Estimated voting center of issen or middle of the forehead, after which the patient must indicate whether the sound is heard best on one of the ears, or whether it is the same. In normal hearing will sound just heard clearly in both ears. If the sound is heard better on a penny, there are indications that there is a perceptivt hearing on the opposite side. However, paradoxically, the sound will be heard best on the bad penny, if you have a konduktivt hearing loss in the ear. Therefore, they always both Rinne and Weber
Audimetrie ( "normal" hearing test):
The patient is fitted with a pair of headphones and will sit in a room where there is so quiet as possible. It provides the hearing threshold for different frequencies, by allowing the patient to hear sounds with varying frequency and strength in the headphones. When the patient hears a tone, he or she mark by pointing to the ear, where the tone could be heard. This determines how well the sound heard when it passes through the air. It is also determined how good bone cord of sound is. This is done at almost the same
In this study gauge Monday how much the ear drum could be put into oscillation of sound waves. There is a special plug, with three small canals in the ear canal. Through the upper channel fed into a special measuring tone, and through the lower measured the sound, which measure the tone induces the ear canal. Sound pressure levels will depend on the ear drum is moving. The third channel can change the pressure in the ear canal.
This method is used for screening babies' hearing. With a very sensitive microphone, introduced into the ear canal, measuring at sounds that are emitted from the inner ear. These sounds emitted both spontaneously and by stimulation with sound. The sounds coming from the small hårceller in the inner ear (see the ears structure and function). If there are no sounds, there are indications that hårcellerne not working, and thus are hearing impaired.
Electric response audiometry (ERA):
Here meter Monday through special electrodes that the electrical response that occurs in the brainstem, after the ear has picked up a sound.
Aids by hearing impairment
Hearing aids work best when konduktive hearing loss. A hearing aid works by amplifying the sound. This is achieved by the fact that there is a small microphone to pick up sound in the surrounding area. The sound is amplified and coming out of a small speaker. Speaker sits in the ear canal, so the sound is sent directly into your ear. There are many different types of hearing aids:
- Ørehænger:Here is the hearing aid behind the ear and are connected to a custom earplug with the speaker through a hose. Earplug will perfectly fit in the ear canal, otherwise will beep hearing aid.
- All in-ear device:In this type of hearing aids is all built into a specially adapted earplug. This hearing is very discreet, since it only just see that it sticks a little out of the ear canal.
- Kropsbårent:Here microphone worn elsewhere on the body than by ear. The microphone is then connected to a wire to an earplug with a microphone. These devices are good for people who find it difficult to cope with the otherwise very small hearing aids, for example. children or gigtpatienter.
- Bone anchored hearing aid: A small screw drilled into the bone behind the ear, and through a dedicated leader sounds transferred from a special hearing to the bone. Vibrations, it occurs in the bone, its input to the snail, which they converted into nerve signals. This type of hearing aids used by people with very severe hearing impairments or who are unable to use an earplug. This may, for example. be due to anatomical abnormalities, or chronic middle, which sustained little liquid flowing out of the ear.
- There arenew hearing aidsThat works inside the ear. For example. could be a mellemøreimplantat, where the sound amplified electromagnetic of a small magnet, the micro-surgery implanted in the small øreknogler in the middle ear.
Most hearing aids are fitted with an induction loop that makes sound can be transferred from, for example. a telephone with a magnetic coil to the hearing aid. It means that the microphone is turned off, and thereby avoid disturbing noise. Many churches, theaters and cinemas are also equipped with audio system with induction loop.
If you have very poor hearing or totally deaf, could benefit from learning to lip-read. You learn to clarify their lips moving in speech and can see what another person says.
This is a relatively new method to treat deafness, so that your hearing can be recycled in whole or in part. The implanted electrodes in the inner ear. These electrodes receives signals from a microphone and send the signal to the hearing nerve. Audio signals can reach the brain, although the inner ear is not working (see details under Operation, which allows deaf hearing again).
This article is formed on the Health Guide on 07.11.07