The secret world inside your ears

Until you experience hearing loss, it’s easy to take your ears for granted. But as audiologists know, hearing is in fact an incredibly complex process, transforming a dog’s bark, clap of thunder or a Mozart sonata into a sensation your brain can respond to, both intellectually and emotionally. That’s a pretty incredible thing – and yet it’s totally invisible to the naked eye.

But imagine if you could shrink yourself down to a microscopic scale – the size of mere microns – hop into a special vehicle, and take a journey inside your ear. You’d discover the secret world that’s far more strange and beautiful than most people realise. So, buckle in and let’s get going.

First stop: the Outer Ear.
Our journey begins at a familiar place with an unfamiliar name: the Pinna. That’s the fleshy part of the ear that sits on the side of your head. Its shape – the curve of the distinctive Antihelix – works to funnel sound down into the Concha. As we enter the ear, that’s the large tunnel looming ahead of us, marking the beginning of what’s known as the ear canal, or External Acoustic Meatus to be particularly formal.

As we journey through the ear canal, we’re likely to come across some sticky yellow clumps. Looks alarming, but it’s actually totally normal – earwax is what your ear uses to clean itself, preventing dirt and bacteria from getting too deep inside.

The ear canal extends about 2.5cm into the ear, but on our microscopic scale, that’s a huge distance. The length serves to protect the more sensitive structures of the Middle and Inner Ear – as well as act as a conduit for sound towards the Eardrum. Which, incidentally, is coming up next in our journey.

Next stop: the Middle Ear.
The large, round membrane in front of us is a key part of your ear – perhaps the most important. Made of three layers of tightly-stretched tissue, the Eardrum – or Tympanic Membrane – picks up the slightest waves of sound and vibrates in response.

At this point, there’s no passage forward through the ear – but for the sake of a story, imagine our journey continues magically on the other side of the eardrum. Here we find the Ossicles, a series of tiny bones that move with each vibration of the Eardrum. One of these – the Stapes, Latin for stirrups – holds the title of the smallest bone in the human body, measuring barely 3mm. This is attached to a round window – the way forward to the next part of our journey, the Inner Ear.

Before we move on though, you’ll notice the Eustachian Tube running alongside us, connecting the Middle Ear to the back of the nose and throat. The tube equalises the pressure on both sides of the Eardrum whenever you yawn or swallow, preventing any damage to the fragile tissues, and ensuring the Ossicles are balanced in perfect equilibrium.

Nearly there: the Inner Ear.
Passing through the round window, we now enter the inner sanctum, where the physical phenomenon of sound becomes something far more abstract: hearing. This is the Inner Ear. It’s a pretty special place.

Here, the vibrating Stapes bone comes into contact with the conch-shaped cavity known as the Cochlea. Think something along the lines of a snail shell, twisting around precisely two-and-a-half times.

This number is important, because the length of the Cochlea allows us to sense whether a sound is high or low in pitch . A high-pitched sound will move the membrane and fluid at the opening of the Cochlea, whereas a lower one will cause motion further inside, deep in the Cochlea’s spiral.

As the fluid moves, it stimulates tiny hair cells – over 15,000 of them – on the Cochlea’s inner wall. If you watched these, from the window of our tiny vehicle, you’d see them waving around like seaweed in the fluid, or Endolymph.

Each of these hair cells is minutely sensitive. When stimulated, a hair cell will fire off a nerve impulse into the Cochlea nerve.

And that’s where the brain begins to take over. Any nerve impulse that reaches the Auditory Cortex in your brain will sound, in your mind, as noise. In other words, you’ll hear whatever it was that caused the vibrations to enter your ear, way back at the opening of the Ear Canal.

Side note: when things go wrong.
Of course, with any process so finely calibrated, sometimes things don’t work the way they should.

Hearing loss usually occurs due to changes in the Inner Ear, but sometimes can also be caused by things going wrong in the Middle Ear, nerve pathways, or the Auditory Cortex in the brain.

Good news is, there’s plenty that can be done to remedy hearing loss and protect your hearing into the future. The sophisticated testing technologies which audiologists use can metaphorically venture into the ear – just like our imaginary vehicle – and determine exactly what needs to be done to get things working again .

So if you’re ever worried about your hearing, it’s easy to make a quick appointment to get things checked out. Your ear is a pretty incredible place, after all, so it’s worth looking after.

To find out more about your hearing health, book a free hearing test.

NHC blog is our place to explore ideas and themes of interest. For professional audiology advice, please contact your local clinic for a consultation.