What’s Behind Modern Hearing Aids? The Science of Sound

Ears are unique, complicated structures that allow us to hear in clear 3d sound. However, they’re also delicate structures, and when something goes wrong, your hearing quality is adversely affected. Luckily modern science and technology can allow you to restore your hearing to a reasonable level via hearing aids. But how do hearing aids work? Here we’ll look at the science of sound and how it makes hearing aids work.

hearing aid

Sound and Hearing, the Basics

To understand how hearing aids assist those with hearing loss, we first need to know how sound works. Sound waves are vibrations that pass through the air until they either dissipate or hit a receptor and are heard. Very loud sound vibrations can be felt with your whole body, but your ears will pick up a normal range of decibels (the measure of sound).

Ears detect sound thus: the outer ear catches and channels sound into the ear canal, down to the eardrum. The eardrum vibrations set three tiny bones in motion to amplify the sound, then pass through the middle ear to the inner ear. In the inner ear is the cochlear, a fluid-filled organ that connects to the brain via 25000 nerves. The movement of the cochlear fluid sends signals to the brain that interprets those vibrations into sound.

Dealing With Loss Of Hearing

The technology behind modern hearing aids is not as simple as it may first seem. With all the tiny moving parts involved, there are plenty of ways the delicate hearing mechanism can go wrong. Different types of hearing aids try to tackle the various causes of hearing loss. They range from simple amplifiers right through to the fantastic cochlear implant that is an option when hearing aids aren’t enough.

The Different Types Of Hearing Aid


The first hearing aids were named ear trumpets – simple hearing tubes held to the ear to magnify nearby sounds. Technology has moved on since these simple devices and hearing amplifiers can look precisely like hearing aids. These devices are not medical grade and only provide a generic increase in sound volume. An amplifier is better for people with normal hearing who find themselves in situations where the sound source is far away.

True Hearing Aids

Hearing aids are medical-grade devices regulated by the FDA and tailored to the user’s specific hearing loss needs. After a hearing test, the data is analyzed and used to work out the individual’s hearing profile. There is a wide variety of hearing aid styles, which allows users to find the type that best suits their hearing loss profile. The most common two styles are In-The-Ear (ITE) and Behind-The-Ear (BTE), both of which have variations.


ITE hearing aids, as the name suggests, sit entirely inside the ear to varying degrees. ITE aids are best for people with mild to moderate hearing loss or who have damage to both the lower and upper sound registers. Where there is a frequency loss in the upper and lower registers, ITE hearing aids filter all sound entering the ear canal. This design allows them to work on correcting the pitch and volume of both registers.

ITE’s range from Completely-in-Canal, through to Low-Profile Hearing Aids. Models in the CIC styles, such as the Eargo, are extremely discreet as they are so hard to see. However, they come with their downsides, such as being difficult to place for those with reduced dexterity. They also have fewer features, partly because of their size and partially because extra features don’t work well within the ear canal.

Less discreet but better for those with reduced dexterity are In-The-Canal hearing aids and Low-Profile hearing aids (which technically aren’t quite ITE as they sit in the bowl of the outer ear). They’re a little larger, so they can accommodate more features such as directional microphones for better sound quality. These features allow them to help a broader range of hearing loss which is beneficial for offering choices.


BTE hearing Aids have the main part of the aid tucked behind the ear and a receiver either in the ear canal or the bowl of the ear. The ITE is excellent for loss of the higher register as the tiny receiver allows low-frequency sounds to filter in naturally. The Oticon More is an outstanding example of this. When the receiver fills the whole ear, devices are brilliant for all types of hearing loss, from mild to profound, as they can be more powerful.

The Inner Workings of Hearing Aids

But how do hearing aids work? At the basic level, they contain a microphone that picks up sounds and a speaker that outputs that sound. Modern hearing aids use digital technology that allows this process to be tailored to the individual’s needs based on hearing tests. Someone who only has damage to the high frequencies will have hearing aids programmed to pick up only those sounds.

Further to this processing, the sounds between the microphones and speakers allow for distortion and distracting ambient sound removal. How the sounds are filtered depends on a person’s needs and the type of device being used. An ITE device won’t filter out just one frequency well, whereas a BTE device with the receiver in the ear can.

Additional features such as multiple microphones for multidirectional sound pick up and Bluetooth connection add to their effectiveness. Older styles of hearing aids have a telecoil for use in close loop circuits, but newer ones use Bluetooth in their place. This technology allows paired hearing devices to work together, much like Bluetooth headphones, without losing a crucial existing function.


Modern hearing aids are impressive, having come a long way from the primary ear tubes of the 1700s. Even a couple of decades ago, most hearing aids were clunky affairs that weren’t great at filtering background noises. Current designs have become streamlined and stylish and make use of digital technology to give precise sound reproduction. So, if your hearing becomes impaired, you can be assured there are solutions.

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