Hearing impairment is when the hearing is affected by a disease, disorder or injury. Deafness is a profound loss of hearing. Leading charity, the RNID, estimates that there are between eight and nine million deaf and hearing impaired people in the UK. This number is expected to rise as the number of people over the age of 60 increases.
Hearing loss can be present at birth (deaf or hard of hearing people) or develop in childhood or adulthood (deafened people). It occurs for a large number of reasons, which can be categorised into conductive and sensorineural.
Conductive means that sound coming into the ear is blocked in some way from travelling to the inner ear. Conductive causes include:
Middle ear infections,
Glue ear,
Wax blockage,
Eardrum injury,
Otosclerosis (a disorder of the middle ear),
and Rheumatoid arthritis.
Sensorineural causes are ones where the pathway the sound travels along is damaged. These include:
Age-related hearing loss,
Acoustic trauma (physical damage to the ear),
Viral infections such as mumps or measles,
Meniere’s disease,
Acoustic neuroma (a non-cancerous growth near the hearing nerves) ,
Meningitis,
Encephalitis,
Multiple sclerosis,
Brain tumours,
and Stroke.
Symptoms
The symptoms of hearing impairment vary depending on the cause. Some people experience sudden profound hearing loss, for example because of a viral infection or severe trauma to the ears, while others notice a gradual decrease in hearing.
Some causes of hearing impairment have symptoms other than sound loss, such as dizziness, whistling sounds in the ear and loss of balance or co-ordination.
Causes
There are a great many causes of deafness and hearing impairment. The biggest single cause is age, called age-related hearing loss (presbyacusis). Most people begin to lose a small amount of their hearing between the ages of 30 and 40 years old. This hearing loss increases with age and by 80 years old most people experience a significant loss of hearing.
Age-related hearing loss occurs because the hair cells that line the sound pathway in the ear begin to die. Commonly, high frequency sounds such as female or children’s voices become difficult to hear, and it is harder to hear consonants like the letters s, t, k, p, and f.
Another common cause of hearing loss is damage to the ear from loud noises (acoustic trauma ) , when part of the inner structure of the ear is injured. People who are exposed to loud noises over long periods are more likely to develop acoustic trauma. This may include people working close to loud music (such as night club staff), people who work with noisy equipment (such as pneumatic drills/compressed air hammers) and people who listen to high volume music through headphones.
After listening to very high noise levels your hearing will shift it’s threshold, causing you to experience muffled hearing or ringing sounds in your ears. This is temporary and your usual hearing should return within a few hours. However, prolonged or intense exposure to very high noise levels can result in a permanent threshold shift or tinnitus.
Diagnosis
In the UK, the NHS is dedicated to screening every newborn baby for hearing impairment, within the first two days of life. Newborn hearing screening (also known as universal neonatal hearing screening), provides the opportunity for children with hearing impairments to be diagnosed as early as possible, increasing their chances of good communication and language development.
The tests itself involves inserting a tiny probe inside the child’s ear. This is not uncomfortable and is carried out while the child is asleep if possible. The probe emits small sounds and checks for a response from the child’s cochlea. If the cochlea does not respond to the test, further tests are carried to determine the cause.
In areas of the country where newborn hearing screening is not yet available, your health visitor is able to carry out the distraction test, a simple set of exercises that monitor the child’s response to sound.
Adult diagnosis
If you think you may have some hearing loss you should visit your GP as soon as possible. Your GP may refer you to a specialist called an otolaryngologist or an audiologist, who will test you further to determine the cause of your hearing loss and work with you to find the best possible treatment.
A simple way to find out whether you need to visit your GP is by answering the following questions. If you answer yes to most of them you may need to investigate the matter further with your GP:
Do you have difficulty hearing over the telephone?
Do have difficulty listening when more than one person in the room is talking?
Do other people complain about the volume of your music or television?
Do you have to concentrate quite hard to understand the other person when you are having a conversation?
Do you often miss the sound of the doorbell or the phone ringing?
Do you often get confused about the direction a sound is coming from?
Do you regularly have to ask people to repeat themselves?
Do the voices of women and children seem harder to understand?
Do you work in a noisy environment?
Does it seem as though everyone is mumbling?
Do you often misunderstand what people are saying?
Can you sometimes hear a hissing, rushing or ringing sound?
Has someone close to you suggested that you may have a hearing impairment?
Treatment
The treatment of hearing impairment will depend very much on the underlying cause; however, the majority of people with hearing impairment find that it is a permanent condition.
There are a number of methods that can be used to enable people with hearing impairments to have an improved quality of life.
Hearing aids
Hearing aids are for people with impaired hearing. They are not a cure as such but increase the volume of sound entering the ear so that people can hear better. They are not suitable for everyone and may not be effective for people with profound hearing loss. It is important that people using hearing aids continue to receive advice and support about assistive hearing devices after they receive their aids, to ensure that their specific needs are being met. Hearing aids are electronic devices made up of a microphone, an amplifier, a loudspeaker and a battery. Modern hearing aids are very small and discreet and can be worn inside the ear. The microphone picks up sound, which is made louder by the amplifier. Hearing aids are fitted with devices that can distinguish between background noise (such as traffic) and foreground noise (such as conversation).
Both analogue and digital hearing aids are now commonly used in the UK, although most aids prescribed through the NHS are now digital. The functions and designs of each device differ according to the needs of the user. After having your hearing tested at the audiology department of a hospital, a technician will take a mould of your ear so that the hearing aid can be fitted perfectly.
There are four different types of hearing aids available though the NHS:
ITE – In the ear devices that sit inside the outer ear.
BTE – Behind the ear devices that sit behind the outer ear and against the head.
BW – Body worn devices, earphones attached to small boxes that clip to the clothes.
Bone conduction aids – similar to the body worn devices in appearance, but the conductor is attached to a headband and held against the bone behind the ear (mastoid).
Cochlear implants
Cochlear implants are used by people with profound deafness. They are made up of two parts, an external sound processor and internal electrodes. Sound is converted to signals by the processor and transmitted to the auditory nerves by the electrodes. This means that cochlear implants are only suitable for people whose hearing nerves are functional.
The implant is inserted during an operation and switched on a couple of weeks later. Implants may be suitable for both adults and children who have not had any success with other hearing aids.
The external part of the implant is worn like a traditional hearing aid, either behind the ear or clipped to the clothes.
BSL
The ability to communicate is very important and loss of hearing can affect your speech as well as your ability to understand other people. Many people with hearing impairments learn to communicate in other ways apart from spoken English. For people who have experienced hearing loss at a later age, lip-reading (watching a person’s mouth movements to understand what they are saying) is a very useful tool.
For people who are born with hearing impairments, it is more difficult to learn to lip-read. People in this situation often learn a sign language such as BSL (British Sign Language), a form of communication using hand movements and facial expressions to convey meaning. BSL is completely different from spoken English and has it’s own grammar and syntax. Other types of sign language are Signed English and Paget Gorman Signed Speech.
Prevention
The ears are fragile structures that can be damaged in many ways. Although it is impossible to prevent many diseases that affect the hearing, it is possible to reduce the risk of acoustic trauma (hearing loss from loud noise).
Turn down your television, radio, music and headphones. This especially important if you have young children in the house.
Use ear protection equipment if you work in a very noisy environment such as a pub, club, and garage, on a building site or in an airport.
Use ear protection equipment in loud concerts, motor races and other events with high levels of noise.
Don’t insert objects into your or your children’s ears. This includes fingers, cotton buds, cotton wool and tissue.
Be aware of the symptoms of common causes of hearing loss, such as Otitis media and Meniere’s disease.
Make an appointment to see your GP as soon as possible if you think you or your child are losing any degree of hearing.