Hearing aids

Published by Bupa's Health Information Team, March 2010.

This factsheet is for people who are considering getting a hearing aid, or who would like information about them.

How the ear works

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About hearing aids

Hearing aids are worn by people who have some level of hearing loss. They can help increase how much you hear if your hearing loss is a result of damage to cells in your inner ear called hair cells. These cells have tiny hairs (cilia) at their tips that pick up sound vibrations. Usually when a vibration is transmitted to the hair cells, the cilia move and produce an electrical signal that is transmitted to the auditory nerve (the nerve connecting the ear to the brain). This travels to the brain where it's processed and you perceive sounds. If the hair cells are damaged, electrical signals aren't created in response to sounds from the outside and so you can't hear. This is called sensorineural hearing loss.

Sensorineural hearing loss can be caused by:

• a disease such as meningitis
• a head injury
• damage to the hair cells caused by loud noise
• certain medicines
• ageing

Hearing loss can also be a result of sound not travelling properly from your outer ear to your inner ear. This is called conductive hearing loss. Depending on what is causing this, you may find that a hearing aid helps.

You may also find hearing aids helpful if you have tinnitus. This is a condition in which you hear sounds, such as high-pitched ringing or hissing, when there is no outside source for them. If you wear a hearing aid, you may not perceive these noises as much and therefore be less disturbed by them.

Having a hearing test

If you think you may need a hearing aid, you will first have to have a hearing test. Your GP can refer you to an audiologist (a healthcare professional who specialises in identifying and treating hearing disorders) or a doctor who specialises in this area of medicine. He or she will ask you to listen to sounds at different pitches and volumes. The results of these tests will help your audiologist or doctor to identify what type of hearing loss you have, and how severe it is. He or she will discuss with you whether or not hearing aids can improve your hearing.

How hearing aids work

A hearing aid increases how loud sounds from your surroundings are. It consists of a microphone, an amplifier and a loudspeaker. The microphone picks up sounds and converts them into electrical signals that go to the amplifier. The amplifier makes these louder and sends them to the loudspeaker. The loudspeaker then converts the electrical signals into sounds that you can hear, feeding them via a tube into your ear canal.

Types of hearing aid

Your hearing aid will either be analogue or digital. These terms refer to how the hearing aid processes sounds.

Analogue hearing aids
Analogue hearing aids convert sound waves into electrical signals, which are then amplified. Your hearing aid can be set with different programmes, depending on what your audiologist recommends as a result of your hearing test. You can switch between programmes to adapt for different environments, such as being in a quiet room with only one or two people, or at a noisy party with lots of people. However, you may still find that it's hard to hear well when you're in busy places because the background noise is also amplified by the hearing aid.

Analogue hearing aids are usually cheaper than digital ones but have now been almost phased out.

Digital hearing aids
Digital hearing aids process sounds by dividing them into pieces and amplifying each one separately. Each piece holds information about the sound's pitch and how loud it is. This means the hearing aid can be set to amplify certain sounds more than others and so is better at getting rid of background noise. This also means that digital hearing aids can be designed more specifically for you. However, it's important to remember that it isn't possible for any hearing aid to amplify only the sounds you want to hear.

Digital hearing aids are newer and have now almost completely taken over from analogue ones.

Wearing a hearing aid

Depending on what type of hearing aid you have, you will either wear it:

• behind your ear
  
• in your outer ear
  
• in your ear canal

Behind-the-ear (BTE) hearing aids have an earmould that you fit into your outer ear. The earmould is connected to a plastic case that you wear tucked behind your ear. This case contains the microphone, amplifier and loudspeaker. Sounds are transmitted through the earmould to your ear. You are most likely to have this type of hearing aid because they can be used for all degrees of hearing loss.

Some newer BTE hearing aids have an open ear fitting. This means that instead of an earmould, there is a smaller, soft earpiece connected to the plastic case by a thin tube. The earpiece fits inside your ear canal and so may be less noticeable than an earmould. You may be recommended this type of hearing aid if your hearing loss is less severe. These BTE hearing aids produce a very natural sound. You may also find it easier to insert this type of hearing aid.

Another type of hearing aid that you may use if your hearing loss is mild to moderate is an in-the-ear (ITE) hearing aid. In this type of hearing aid the electronic parts are all inside the plastic case and this fits into your outer ear. These hearing aids are usually less noticeable than BTEs.

There are two types of canal hearing aid - in-the-canal (ITC) and completely in canal (CIC). The smallest of these fit inside your ear canal so they can hardly be seen. Again, these hearing aids will only be suitable if you have mild to moderate hearing loss. You may find these difficult to use if you have problems using small controls.

Other less common types of hearing aid include body-worn hearing aids and bone conduction aids. Body-worn hearing aids have a small box that contains the electronic parts and connects to an earmould by a wire. This type of hearing aid can be very powerful and may be helpful if you have sight problems or find it difficult to work small controls.

A bone conduction aid may help you if you have conductive hearing loss. Bone conduction aids consist of a small vibrator that you wear with a headband to hold it in place behind your ear. Vibrations go directly to your inner ear through your skull.

You may also wish to consider a bone anchored hearing aid (BAHA) if you have conductive hearing loss. You will need to have an operation to insert a small metal implant into the bone behind your ear. A sound processor is then attached externally to the implant.

Caring for your hearing aid

Your audiologist will give you instructions about how to care for your hearing aid so that it works well and lasts as long as possible. However, there are a number of points to remember that you may find helpful.

• Clean your hearing aid regularly with a soft, dry cloth to remove any earwax. You will be given instructions on how to do this.
  
• If you have a BTE hearing aid, it's usually suggested that you separate the earmould from the rest of the hearing aid and wash it. However, it's important that you check with your audiologist before doing this. When you're not wearing your hearing aid, store it carefully in a box in a cool, dry place.
  
• Turn off your hearing aid when you're not using it.
  
• Change the batteries as soon as they stop working.

Living with a hearing aid

You may find it takes a while to get used to wearing a hearing aid. It's important to wear it as much as possible and practise using the controls and different settings. Your audiologist will be able to give you advice about using your hearing aid in different environments. He or she can also help if you have any problems with your hearing aid.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.