How Do Hearing Aids Work?

A hearing aid is a small electronic device that is worn in, or behind, the ear. It amplifies sounds, thereby making it easier for the wearer to hear more clearly in both quiet and noisy locations. As such, it enables the wearer to listen and communicate more easily.

Hearing aids are battery-powered, and function using either rechargeable or disposable batteries.

A hearing aid comprises three basic parts: a microphone, amplifier, and a speaker. The microphone picks up sounds from the environment and converts them into a digital signal. This is then passed to the amplifier, which is home to a processor, or small computer, if you like. Depending on the user’s hearing profile, the digital signal can be processed by the amplifier in a number of ways.

Dr Marquitta Merkison, associate director of audiology practices at the American Speech-Language-Hearing Association, says that the majority of people lose the higher frequencies in their hearing spectrum.

“They can hear the bass in a voice just fine; but they lose the high sounds – the ‘T’s and ‘K’s in certain spoken words, for example. In this case, their hearing aid would be tweaked so that it doesn’t boost any bass frequencies, just the high frequencies that have been limited or lost.” If a person’s hearing is reduced at all frequencies, the processor would simply boost all sound frequencies equally.

Once the sound has been amplified correctly for the user, the signal is sent to the speaker. The speaker sends the newly processed, boosted signal directly into the inner ear of the user, allowing them to hear more clearly.

The amplified sounds from the hearing aid are easier for the surviving sensory hair cells of the ear to pick up and transmit to the brain. If a person has more severe hearing loss, then more amplification will be needed.

How common is hearing loss?

About 15% of Americans over the age of 18 years have trouble hearing, which is around 38 million people. Hearing loss also becomes much more common as people get older, with nearly 80% of people over 70 experiencing hearing loss in at least one ear. According to the Hearing Loss Association of America, only one out of every five Americans who could benefit from a hearing aid actually wears one.

Hearing loss is often the result of damage to the sensory hair cells in the ear, which can happen as a result of ageing, disease or prolonged exposure to very loud noises. When the hair cells are damaged, this means that only the surviving, undamaged cells can detect sounds and pass them on as signals to the brain. The greater the damage to a person’s hair cells, the more severe the hearing loss.

Do I need a hearing aid?

If you notice that you’re struggling to hear or understand other people when they’re talking, feeling that they “mumble” when they speak to you, for example – or you need to listen to music or the television at a higher volume than others, or have difficulty hearing on the phone, you may be experiencing hearing loss. Hearing loss is often pointed out to people by their friends or family members, who have to repeat themselves many times to be heard and understood.

Dr Merkison says there are two main types of patients she typically sees: “The first type of patient has experienced gradual hearing loss due to ageing or working in loud environments for long periods of time. The second type of patient has had an accident or medical event that has instantly affected their hearing.”

Hearing loss can lead to frustration and difficulty when communicating with others. A hearing aid can significantly improve a person’s quality of life.

Will a hearing aid restore my hearing back to normal?

Unfortunately, no. “Hearing loss is permanent”, says Dr Merkison. “As soon as you remove your hearing aid, you lose the benefit of it. It’s important to wear the hearing aid as often as you can, since it will help you acclimate to hearing the sounds that you may have lost in your hearing spectrum.”

What does it sound like when you wear a hearing aid?

Commonly, people lose the high-frequency sounds in their hearing spectrum but have little issue hearing low, bass frequencies. Those who first wear a hearing aid often describe the sounds they hear as “tinny”, similar to that you might hear from a small speaker – the unit on a cell phone, for example – that handles bass poorly.

However, this is simply because the wearer, over the gradual degradation of their hearing, is no longer familiar with hearing high-frequency sounds. Again, Dr Merkison’s advice here is that regular and consistent use of the new hearing aid will help the user to acclimate to the sounds they’re now experiencing. Ongoing support from your audiologist is available if your hearing aid requires further tweaks.

What if my hearing aid is not helping?

If you feel your hearing aid is not delivering the benefit you need, you should discuss your experience with your audiologist. It could be that the settings on your hearing aid simply require adjusting.

However, there is a limit to the level of amplification a hearing aid can deliver. If a person’s inner ear is too damaged, a hearing aid may be ineffective. In this case, a cochlear implant may be the best option.

READ NEXT: Types of hearing aids, explained

How will an audiologist test my hearing?

“An audiology test is completely painless, and usually very quick”, explains Dr Merkison. “It’s performed in a quiet, soundproofed environment. Initially, you’ll hear a series of beeps, in high and low frequencies, from different directions, with the aim to identify the lowest volume of each frequency you can hear.”

The second part of the test is arguably more important, says Dr Merkison. “This is similar to the beep test but with spoken words and sentences. We want to assess how much speech you can both hear, and understand, and the lowest volume for each of these”, she adds.

What other advice can the audiologist give me?

“It’s important to know that when you go to see the audiologist, it doesn’t mean you’ll return home with a hearing device”, Dr Merkison says. “What you will return with is information about your level of hearing loss, available options and how we can help you.”