Understanding how hearing aids work

Failing to address hearing loss can lead to becoming socially isolated, unable to hear clearly what’s going on around you and eventually becoming excluded from conversations or other social interactions. This gradual ‘shutting off’ from the world also reduces mental stimulation and can even contribute to dementia.

Around 90% of people who struggle to hear clearly are suffering from ‘sensorineural hearing loss’, which involves damage to the cochlea, deep inside the ear. It can be caused by infections, head trauma, sustained exposure to loud noise or simply through ageing. In the simplest terms, it’s one of the parts that starts to wear out and no longer function as well as it used to.

However, hearing aids – especially modern digital hearing aids – can make a big difference and keep people connected to the world of sound around them. So how do they work?

On the simplest level, hearing aids detect and amplify sound. The first ‘hearing aid’ was a hand cupped around the back of the ear, making it a more effective receiver. Later developments have refined this basic principle. Hearing aids comprise four basic parts:

• A microphone picks up sound around the user, converts it to an electrical signal and sends it to the amplifier
• The amplifier increases the volume of the signal and sends it on to the receiver
• The receiver (or speaker) converts the signal back to sound and sends it into the ear.
• A battery provides the electrical charge to power the hearing aid.

There are different types of hearing aid; some are worn behind the ear (BTE), some in the ‘bowl’ of the outer ear (ITE), some deeper in the ear canal (ITC) and some completely in the canal (CTC). Different types work better for different people, depending on the extent and type of their hearing loss, but it’s also important to realise that not everyone will benefit from a hearing aid. Equally, a hearing aid won’t completely restore normal hearing.

Having said that, most people will experience a significant improvement in their hearing. Some types of hearing aid are larger and more noticeable than others, though most modern designs are pretty discreet. Some smaller hearing aids are almost impossible to spot, but generally speaking, the smaller a hearing aid is, the more it costs and the shorter its battery life.

Older ‘analog’ hearing aids simply amplify sound, but the trouble is they pick up and amplify all sounds equally. In a noisy situation this can be very confusing, with lots of different sounds competing. Some settings can be adjusted, but generally speaking analog hearing aids are not that ‘smart’. Newer ‘digital’ hearing aids are more sensitive, able to distinguish between different sounds and provide a much clearer quality.

They contain a computer chip which intelligently analyses and processes the sound. Taking into account the user’s type of hearing loss and particular listening situation, it amplifies the sound you want and filters out background noise. Digital hearing aids are more adjustable and customisable and some can even by set remotely by an expert audiologist, to best suit the user’s needs. One analogy might be the difference between an old analog mobile phone, which can only make calls and sent texts, and a new digital smartphone, which can do a whole lot more. Of course, a smartphone is a little more expensive too.

You might choose to use a hearing aid in one ear or both, depending on your hearing loss and the cost of the hearing aids. If you have hearing loss in both ears it’s generally better to wear two, and the latest designs work in tandem through a wireless signal to produce one natural sound, rather than competing sounds from each hearing aid working independently of the other.

Changing the small batteries in hearing aids could also be a problem for some older people, requiring considerable dexterity. Technology is overcoming this through rechargeable batteries inside hearing aids which can be recharged as a whole unit, without the need to remove the batteries. Simply recharge the hearing aid when it’s convenient, typically overnight while you sleep.

For people with more severe hearing loss, there are other options, including ‘cochlear implants’ and ‘bone-anchored hearing aids’, bit these more complex systems warrant a separate article. If you’ve tried a hearing aid in the past and found it not to your liking, don’t write them off as not for you. It could be that you used an analog type and that a newer digital aid will give much better results.

If you’re worried about hearing loss, speak to your doctor, who might then refer you to a specialist audiologist for further tests and advice. Some retailers or pharmacies also offer free hearing tests, which could be a good starting point. Above all, don’t ignore hearing loss or accept it as inevitable – you can almost always enhance your quality of life with the right hearing aid.