About hearing loss
Hearing loss affects around two out of 10 adults in the UK. Most of these people are over the age of 60 and have lost their hearing gradually (presbyacusis), but hearing loss can occur at a younger age. In the UK, one in every 840 children is born severely or profoundly deaf each year.

Sound and the ear
Sound reaches your ear as sound waves, which cause vibrations that the ear turns into electrical signals. These signals travel to the brain where they are converted into meaningful information, such as language or music.

The ear consists of three parts: the outer ear, the middle ear and the inner ear.

The outer ear is the visible part of your ear. It collects sound, which then travels down your ear canal (external auditory meatus) to your eardrum (tympanic membrane).

The sound waves cause your eardrum to vibrate. This vibration is passed on to the middle ear, which consists of three small bones called the 'ossicles'. These amplify and conduct the vibrations to the inner ear.

The inner ear contains the cochlea, which is shaped like a snail shell. The cochlea is full of fluid and contains tiny hair cells. The ossicles transmit the vibrations to the fluid inside the cochlea, causing the hair cells to move. The movement of the hair cells produces an electrical signal that travels along the auditory nerve to your brain. Different types of hair cell pick up different frequencies (pitches) of sound.

Symptoms of hearing loss

If you have hearing loss:

• you may be finding it difficult to hear and understand people when you're in a noisy place
   

• you may have earache and/or a continual ringing in your ears

If you have any of these symptoms, you should see your GP.

Causes of hearing loss
There are many possible causes of hearing loss. These can be divided into two basic types, called conductive and sensorineural hearing loss.
Conductive hearing loss

This is caused by anything that stops sound moving from your outer ear to your inner ear. The following are possible causes of conductive hearing loss.

• Middle ear infections (acute otitis media).

• Collection of fluid in the middle ear - 'glue ear' (otitis media with effusion).

• Blockage of the outer ear, usually by wax.

• Otosclerosis, a condition where the ossicles of the middle ear harden and become less able to vibrate.

• Damage to the ossicles, for example by serious infection or head injury.

• Perforated (pierced) eardrum, which can be caused by an untreated ear infection (chronic suppurative otitis media), head injury or a blow to the ear, or from poking something in your ear.

Sensorineural hearing loss
This is caused by damage to the pathway between the inner ear and the brain. It affects sound intensity and makes it more difficult for you to recognise complex sounds.

The following are some possible causes.

• Age-related hearing loss (presbyacusis). This is a natural decline in your hearing. Many people get this as they get older because of damage to the hair cells in the cochlea.

• Damage to the hair cells by loud noises (acoustic trauma). This is more likely to happen if you work in a noisy place.

• Certain infections such as measles, mumps or meningitis.

• Ménière's disease, which causes hearing loss, dizziness and tinnitus (a persistent ringing in the ears).

• Certain medicines, such as some powerful antibiotics, can cause permanent hearing loss. At high doses, aspirin is thought to cause temporary hearing loss and tinnitus.

• Certain cancer treatments, such as chemotherapy and radiation therapy, can cause hearing loss.

• Acoustic neuroma. This is a benign (non-cancerous) tumour affecting the auditory nerve causing deafness and tinnitus.

• Cholesteatoma (benign skin growth) in the middle ear, causing deafness and vertigo (sensation of movement when you're standing still).

Mixed hearing loss is a combination of conductive and sensorineural hearing loss.

Diagnosis of hearing loss

In adults, hearing loss may be very gradual, as in age-related hearing loss, or it can be very sudden, as in some viral infections of the inner ear. If you, your friends or your family think that your hearing is getting worse, you should see your GP. If you have sudden hearing loss in one or both ears, you should seek immediate advice.

Your GP will ask you about your symptoms and examine you. He or she may also ask you about your medical history.

Your GP will want to know how your hearing loss has developed and what sort of problems it causes. He or she may then perform a hearing test or refer you to either an otolaryngologist (a doctor who specialises in ear, nose and throat disorders); an audiologist (a specialist in hearing) or an audiovestibular physician (a doctor who specialises in hearing, balance and communication problems).

Hearing tests
You may have the following tests.

• Whispered speech test. Your GP will whisper a combination of numbers and letters behind you and check if you can hear anything by asking you to repeat the combination. Your GP will probably move further away from you each time to test the range of your hearing.
   

• Tuning fork test. Different tuning forks can be used to test your hearing at a variety of frequencies. They can also help determine the type of hearing loss.
   

• Pure tone audiometry. An audiometer produces sounds of different volumes and frequencies. During the test, you're asked to indicate when you hear a sound in the headphones. The level at which you can't hear a sound of a certain frequency is known as your threshold.
   

• If your hearing loss has a sensorineural cause, a number of tests can be performed to pinpoint where the problem lies.
   

• If your hearing loss has a sensorineural cause, a number of tests can be performed to pinpoint where the problem lies.
   

• Otoacoustic emissions. This is used to measure your cochlear function by recording signals produced by the hair cells.
   

• Auditory brainstem response. This measures the activity of the cochlea, auditory nerve and brain when a sound is heard.

If your GP thinks your hearing loss is due to an acoustic neuroma or cholesteatoma, a magnetic resonance imaging (MRI) scan of your head may be recommended.

Treatment of hearing loss
Self-help

You can make it easier to hear and understand people by:

• making sure there is light on the face of the person you're talking to, so you can see their lips moving

• sitting close to the person you're talking to

• sitting so that your better ear is close to the person you're talking to

Medicines
If you have a bacterial infection of the middle ear, it can be treated with antibiotics. Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.

Non-surgical treatments
If your outer or middle ears are blocked by ear wax, a nurse will be able to remove the blockage with a syringe.

If there is no cure for your hearing loss, a hearing aid for one or both ears may help. Hearing aids can work for both conductive or sensorineural hearing loss. Many different types of hearing aid are available, and your audiologist will advise you as to which type best suits your needs.

Surgery
Perforated eardrums usually heal by themselves, but if you have a large perforation you may need to have surgery to repair it.

An acoustic neuroma or cholesteatoma can be removed by surgery. Ossicles affected by otosclerosis can be treated with surgery.

When a hearing aid doesn't give enough sound amplification (eg in profound deafness), a cochlear implant - sometimes known as a bionic ear - may help. This device turns sound into an electrical signal that travels, via electrodes implanted in your cochlea to your auditory nerve, allowing you to hear sound. Cochlear implants work well in most people.



 

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