How we hear
The ear has three parts: the outer ear, the middle ear and the inner ear. Each section helps to move sound through the hearing process. When a sound occurs, the outer ear carries it along the ear canal to the eardrum. The sound causes the eardrum to vibrate. This in turn causes three small bones inside the middle ear (malleus, incus, stapes) to move. This movement travels into the inner ear (the cochlea), where it causes tiny hairs to move within a fluid. These hairs convert the movement into hearing signals, which are then transmitted to the brain, where the sound is registered.
Causes of hearing loss
Hearing loss occurs when sound is blocked in one of the three areas of the ear. The most common cause of hearing loss, and one of the most preventable, is exposure to loud noise. Infections, whether of the ear or elsewhere in the body, are also a major contributor to hearing loss.
- In the outer ear: a build-up of earwax, infections that cause swelling, a growth in the ear canal, injuries or birth defects can all limit hearing in the outer ear.
- In the middle ear: fluid build-up is responsible for the most common infections and blockages of the middle ear. Fluid in the middle ear prevents the bones from processing sound properly. Tumours, both benign and malignant, can also result in hearing loss in the middle ear.
- In the inner ear: the natural ageing process reduces hearing through damage to the cochlea (the mechanism that converts sound vibrations into signals for the brain), the vestibular labyrinth (which regulates balance) or the acoustic nerve (the nerve that sends sound signals to the brain). In addition, inner ear infections, Meniere's disease and other nerve-related problems contribute to hearing loss in the inner ear.
Other causes of hearing loss
- Presbycusis: age-related hearing loss, such as difficulty hearing in noisy places, difficulty understanding what people say, or no longer registering softer sounds.
- Hereditary and genetic causes: there is a wide variety of genetic or inherited diseases and syndromes that can cause hearing loss. Some, such as rubella (German measles), occur when a pregnant mother has the illness, which causes hearing loss in the baby. Other, rarer hereditary and genetic causes include CHARGE syndrome, Connexin 26 disorder, Goldenhar syndrome, Treacher Collins syndrome, Usher syndrome, Waardenburg syndrome and otosclerosis (the growth of spongy bone tissue in the middle ear).
Most causes of outer ear hearing loss can be corrected. However, middle and inner ear problems can lead to permanent hearing loss, which is why it is important to seek medical care promptly if you have problems with your hearing.
Types of hearing loss
There are four types of hearing loss:
- Conductive hearing loss
- Caused by conditions that block the transmission of sound through the outer ear and the eardrum into the middle ear.
- Sensorineural hearing loss
- Damage to the inner ear that occurs as part of the natural ageing process.
- Mixed hearing loss
- Refers to people who have both conductive and sensorineural hearing loss. Most people experience more than one type of hearing loss.
- Central hearing loss
- Occurs when the central nervous system fails to send a readable signal to the brain; this is known as central auditory processing disorder. People with central hearing loss can generally hear all sounds, but cannot separate or process them.
Hearing loss is measured in four degrees: mild, moderate, severe or profound. The degree of hearing loss guides the choice of the most suitable form of treatment, case by case.
Treatments for hearing loss
The location, type and degree of hearing loss influence the choice of treatment for each hearing problem. The most common treatment options include:
- Antibiotics, decongestants and pain medication to overcome ear infections.
- Myringotomy, an incision in the eardrum that allows fluid to drain from the outer ear. A tube may be placed in the Eustachian tube (the part of the anatomy that connects the middle ear with the back of the throat) to keep it open and allow normal drainage of fluid. This technique may be recommended for people who develop frequent ear infections.
- Hearing aids.
- Surgery to remove benign or malignant tumours, or to correct problems related to the bones or the nerves.
If you experience sudden or prolonged hearing loss together with dizziness, fever or pain, please contact our clinic immediately and arrange an appointment with one of our ENT specialists. We will carry out a physical examination as well as a hearing test to determine the type and severity of your hearing loss. We will then recommend the most suitable treatment.