What is it about ?
Each ear is connected by the auditory nerve to the hearing center in the brain. The ear is made up of the outer ear, which includes the pinna and the external ear canal, which is closed by the eardrum. Behind the eardrum is the middle ear, which has three connected ossicles (hammer, anvil and stirrup). Further into the inner ear, there is a coiled, spiral-shaped structure (the cochlea).
The pinna picks up sound that is transmitted inward along the ear canal. There, he stumbles on the eardrum. This causes vibration in the ossicles. This vibration is converted into a small electric current in the inner ear. This current travels along the auditory nerve to the brain, where it is converted into a perceptible sound.
There are two types of deafness: conductive deafness and sensorineural deafness:
- in the case of conductive hearing loss, the problem lies in the external auditory canal, at the level of the eardrum or in the middle ear. The ear canal may be blocked by earwax (plug). Damage to the ossicles can be a consequence of infection or rheumatic disease. The ossicles cannot then vibrate properly. This is the case when there is fluid in the middle ear. There may also be a small hole in the eardrum (this is referred to as a “pierced eardrum”). In this case, the sound is not or not sufficiently transmitted to the interior.
- hearing loss can be the result of a problem in the inner ear, the auditory nerve, or the nerve pathways in the brain. In this case, we are talking about sensorineural deafness. Damage to the cochlea or the auditory nerve prevents the conversion of sound into an electric current. As a result, we no longer hear the sound. The causes can be: prolonged exposure to noise (at work), but also sudden violent noise such as an explosion. It is often a question of a hereditary predisposition to sensorineural deafness.
The power of a sound is expressed in decibels (dB). At a music festival, sound peaks up to 130dB, heavy traffic produces 80dB and normal conversation – 60dB. Calm corresponds to less than 30 dB. Hearing rehabilitation is necessary when, in a hearing test, the better ear only achieves a hearing level of 20 dB or less in children and 30 dB or less in adults. Technical rehabilitation means that hearing loss is compensated by the use of hearing aids.
What is its frequency?
Hearing loss is a common problem, which occurs at any age: in young children (often due to the accumulation of fluid in the middle ear) as in the elderly (hearing loss associated with aging (presbycusis) ).
Average hearing loss increases with age. It is estimated that 1 in 5 people have a hearing loss of at least 25 dB and 1 in 20 people have a hearing loss of at least 45 dB. About 1 in 20 people would need a hearing aid. In fact, only 1 in 30 to 1 in 100 people have such a device. This is because many people think that their hearing loss is less severe than it actually is, or that it is part of the natural aging process. In addition, the price is sometimes a barrier to purchasing a hearing aid. Also, many people do not want to wear a hearing aid after a trial period.
How to recognize it?
Conductive hearing loss is more common in children, due to the buildup of fluid or pus behind the eardrum. Hearing loss is often located in one ear. You may notice that the child is listening with the other ear and that he turns his head to point his good ear towards the origin of the sound. It will also tend to turn up the volume of music or television. Sometimes the first sign is poorer school performance or delayed speech and language development. For their part, adults notice on their own that their hearing is reduced.
Sensorineural hearing loss can start suddenly or gradually. Sudden deafness can occur after a single loud noise, such as an explosion. But deafness usually sets in gradually. You can still follow a two-person conversation, but it is increasingly difficult to follow a group conversation. Hearing loss is also bilateral (it therefore affects both ears).
Diminished hearing can also be associated with the perception of background noise (you hear the conversation, but you do not understand it) and ringing in the ears (tinnitus).
How is the diagnosis made?
The doctor will start with a simple examination of the ear to check if there is fluid behind the eardrum and whether the eardrum is intact. In case of hearing problems, he will refer you to the otolaryngologist (ENT). This will evaluate the functioning of the ossicles and will check if your hearing is impaired and, if so, on what wavelengths (frequencies). He will also assess whether it is conductive deafness or sensorineural hearing loss.
What can you do ?
Always protect your ears against extreme noise, whether at work or in your spare time. Use noise-canceling headphones, especially for children.
Hearing loss can be compensated by a number of devices:
- communication amplifiers amplify speech and environmental sounds for people who cannot wear a hearing aid.
- Doorbells, telephones, smoke detectors and crying alarms for children can be equipped with a high frequency tone or a light signal.
- an amplifier adapter can be installed on the phone.
- a headset can be plugged into the radio, television, or computer.
- some public buildings are equipped with fixed induction loops that the visitor can use.
- at school, an FM device can be used; the teacher speaks into a microphone connected to the student’s hearing aid.
What can your doctor do?
Conductive hearing loss can often be cured. Sometimes a little intervention is needed to restore hearing. If there is fluid behind the eardrum, placing a drain can help drain the fluid. This drain usually stays in place for a while before being released naturally, or extracted if necessary. A small hole in the eardrum can be repaired. Sometimes an ossicle is removed and replaced with a prosthesis.
Sensorineural hearing loss is usually irreversible (and therefore permanent), but can be corrected with a hearing aid. There are different types depending on your possibilities, your wishes and your budget. They can be worn behind the ear (or over hearing glasses), inside the ear, or on the body. Placing devices inside the ear requires skill and good eyesight. This can be a problem, especially in older people.
If an operation or a hearing aid does not provide sufficient improvement, an acoustic hearing implant can be tried. In this case, the hearing aid is fully or partially implanted. Cochlear implants are useful for people who can (hardly) hear anything. These devices are introduced into the cochlea and stimulate the auditory nerve to generate an electric current.
Want to know more?
- Ear (image) – Larousse
- Hearing (video) – microbiologiemedicale.fr
- The cochlear implant, here, Where to find on this page of Cliniques St Luc UCL
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