Why can't I hear in space?

Sound needs something to travel through, like air or water. It moves by shaking the tiny bits that make up air. Space is empty — there is almost no air at all — so there is nothing for the sound waves to shake. That is why astronauts in space cannot hear each other through the empty space and must use radios instead.

Why does loud noise hurt my ears?

Very loud sounds are big, strong vibrations. They shake your eardrum and the tiny parts inside very hard. If a sound is too loud or goes on too long, it can tire out or even damage the tiny hair cells inside your ear. That is why you should never turn music up very loud or stand close to very noisy things.

The Ear and How We Hear | Physics

How sounds reach you

Close your eyes for a moment and just listen. You might hear voices, a clock, birds, or a car outside. All of those sounds are travelling through the air and reaching your ears right now. But how does a sound that started across the room end up as something you can hear inside your head? Let's follow a sound on its amazing journey into your ear.

Sound starts with a wobble

Here is the big secret: every sound is made by something vibrating. To vibrate means to shake very quickly back and forth. When you bang a drum, the drum skin shakes. When you talk, parts inside your throat shake. When a guitar string is plucked, it buzzes back and forth so fast you can hardly see it.

You can feel this yourself. Gently rest your fingers on your throat and hum a long mmmmm. Can you feel the buzzing? That is your voice vibrating. Stop humming and the buzzing stops. No vibration means no sound. You can learn more about this in our lesson on sound and how we hear.

Sound travels as waves

When something vibrates, it shakes the air all around it. The air gets pushed and squashed, then stretched, over and over. This makes invisible ripples called sound waves that spread out in every direction — a bit like the ripples that spread when you drop a stone in a pond.

These sound waves travel through the air until some of them reach your ear. Sound can travel through water and through solid things too, which is why you can hear a knock on a door or splashes when you are underwater in a pool. But sound always needs something to travel through. If you would like to dig deeper, see waves and vibrations.

The outer ear: a funnel for sound

The part of the ear you can see and touch is called the outer ear. It is shaped like a curvy funnel, and that shape is no accident. It helps catch sound waves from the air and guide them into a tunnel called the ear canal.

Have you ever cupped your hand behind your ear to hear better? You were making the funnel bigger, so it caught even more sound. That is exactly the job your outer ear does all the time.

The eardrum: a wobbling skin

At the end of the ear canal is a thin, tight piece of skin called the eardrum. It is stretched tight like the skin on a real drum. When sound waves arrive, they push against the eardrum and make it wobble very fast, back and forth, copying the vibrations of the sound.

The eardrum is tiny and very delicate, which is one big reason you should never poke anything into your ear. It does a huge job from a very small space.

Inside the ear: tiny bones and a curly tube

Behind the eardrum are the three smallest bones in your whole body. People sometimes call them the hammer, anvil, and stirrup because of their shapes. When the eardrum wobbles, these little bones wobble too, passing the vibrations along and making them a bit stronger as they go.

The bones pass the wobbles to a curly part shaped like a snail shell called the cochlea. The cochlea is filled with liquid and lined with thousands of tiny "hairs". When the liquid wobbles, the tiny hairs wobble too, and they turn the wobbles into electric messages.

The brain: where hearing happens

Those messages zoom along a nerve straight to your brain. Just like with seeing, your brain is the real listener. It takes the messages and works out, "That's a bell!" or "That's Mum calling me!"

All of this happens in less than a second. From a wobble in the air to a thought in your head — your ears and brain are a brilliant team.

Why we have two ears

Have you ever wondered why you have an ear on each side of your head? It helps you tell where a sound came from. If a dog barks on your left, the sound reaches your left ear a tiny bit sooner and a tiny bit louder than your right ear. Your clever brain notices this and tells you, "The bark came from the left!" With only one ear, that would be much harder.

The journey of sound, step by step

Something vibrates — say, a ringing bell.
It makes sound waves in the air.
The outer ear funnels them into the ear canal.
The waves wobble the eardrum.
Three tiny bones pass the wobble along.
The cochlea turns the wobble into messages.
A nerve carries the messages to the brain, which says, "A bell!"

Try it yourself! 🧪

Experiment 1 — See a sound wobble. Stretch some cling film tightly over the top of a bowl so it is smooth and tight, like a little drum. Sprinkle a few grains of rice or sugar on top. Now hold a metal tray or pan close to it and bang it (not too hard), or shout "HEY!" near it. Watch the rice jump and dance! The sound made the air wobble, the wobbling air shook the cling film, and the shaking film tossed the rice into the air. That tight film is acting just like your eardrum.

Experiment 2 — Find the sound. Sit in the middle of a room and close your eyes. Ask a grown-up or friend to quietly move around and gently click their fingers or tap two spoons in different spots — to your left, behind you, in front. Each time, point to where you think the sound came from, then open your eyes to check. You will be surprised how good your two ears are at this. You are using both ears together, just like your brain does every single day.

So the next time you hear your favourite song, remember the journey: wobble, waves, funnel, eardrum, bones, cochlea, nerve, brain. Hearing is a kind of superpower — and now you know exactly how it works.

The Ear and How We Hear

Key takeaways