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Ear model

Public summary: 

Use our large-scale model of the ear to discover how it enables you to hear sounds.

Anatomical model of the ear, with removable parts.
Useful information
Kit List: 

Anatomical model of an ear.
Water filled plastic tube to demonstrate the semicircular canal.

Frequency of use: 

-show the model; it's important to orientate them; i.e.the white bit is the skull; get them to think about that the majority of their own ear is actually inside the skull
-take model apart; look at/identify individual bits - what might they do?

-point out semicircular canals on the anatomical model; show them the water filled circular tube and say that that's what they look like inside
-get them to spin the water filled tube- the pink bits move- so the fluid moves as well (for things to say please see below)
- what else is important for balance: get them to stand on one leg and let them close their eyes; is it easier or harder with their eyes closed? (for things to say please see below)

If the kids are a bit older, they will often know quite a bit about how hearing works. However, they often know very little about balance, so it's good to talk about that a little more.
If the kids are really interested and know a lot already, you could talk a bit about soundwaves.



What ears are for?
- All our senses, ears, eyes etc there so we can get information from outside into our brains. In the case of ears we want to convert sound into something we understand, music, speech or whatever.

- The outside bit of ear's a funny shape, helping it to collect sounds and tell us a bit about where they are coming from. Sound makes the air vibrate, different sounds make it vibrate different amounts. This causes our ear drum to vibrate.
-If you've got the direction-swapping device (ear defenders with crossed tubes and cones) to hand, you can use this to explain how we locate sounds according to which ear they arrive at.

Ear drum:
- Lots of kids have heard of this. I'm often asked about grommets (lots of kids have these): They are
small tubes that can be put through the eardrum to help drain fluid and allow air to circulate in the middle ear.

Bones in the ear:
- Inside the ear we have the three smallest bones in our body. Think how much bigger this model is compared with our ears. The bones join the ear drum with the inside bit of our ear, they vibrate as well. They help make sure that as much of the energy from the sound outside gets passed into the inner bit of our ears as possible. There are also tiny muscles attaching to them that can help protect our ears against sounds that are too loud. The bones are called the malleus, incus and stapes (also known as the hammer, anvil and stirrup) because of their shape.

Inside the ear:
- This is really clever and quite complicated (!). Tiny little cells with hairs on can detect the vibrating. We have nerves taking messages from our ears to our brains to tell us about the type of sound we're hearing, they're a bit like electrical cables so these tiny cells convert the vibration into an electrical message.
- Compare ear model to skull to see where all this is going on.

What happens in people who are deaf?
- The message is lost somewhere along the way. Maybe the sound cant get to the eardrum because we have wax in our ears. We can get infections inside our ears behind our eardrums where the little bones are, if this gets filled with fluid the bones cant vibrate properly. Or the cells with hairs on or the nerves can be damaged so the message can't get from our ear to our brain.


Do we use our ears for anything else?
- They help us to balance too, so even if we close our eyes we still have some idea of which way up we are. Get them to stand on one leg and close their eyes or something. What happens when they close their eyes? It's more difficult, so we need our eyes for balance, too.
- There are little tubes filled with liquid at different angles, which are called semilunar canals. When we move, the fluid moves (bit like a spirit level?!). We can sense the fluid moving-that's how our brain knows that we're moving - can then help us balance movements. What happens when we get dizzy? We spin around lots so the fluids move round the tubes (use model), when we stop the fluid keeps moving for a bit after. So our ears think we're still moving, our eyes say we've stopped and our brains get confused. Similar idea in car sickness - when you look down at a book, your eyes start to think you're not moving, but your ears still think you are, so brain get confused again.


Ever noticed ears going funny in tunnels/on aeroplanes?
- Get them to breathe out, and then swallow while pinching the nose shut and with the mouth closed. There's a tube between our ear and throat that is normally closed but is opened when we yawn or swallow. It helps us by equalising the pressue in the inner ear and in the outside world, because if the air pressure (or better explain pressure without saying the word somehow!) around us is different to inside our ears our eardrum gets pulled in or pushed out, and opening the tube equalises the pressure, allowing the eardrum to return to its normal position. This is why sucking sweets helps when you go up in aeroplanes - I think because the sucking and swallowing causes the tube to open so the pressure difference is equalised frequently and so your ears don't 'pop'.

What is sound?
Sound travels in waves. It's like when you throw a stone into a lake- waves travel from it. The stone is the sound (i.e. a word we say), and our words/music etc. can make waves in the air, just like the stone can make waves in water; the eardrum in our ear can then pick up the waves; our ear converts these waves into signals, they travel to the brain, the brain interprets them as words/music

Risk Assessment
Date risk assesment last checked: 
Tue, 07/01/2020
Risk assesment checked by: 
Date risk assesment double checked: 
Fri, 24/01/2020
Risk assesment double-checked by: 
Beatrix Huissoon
Risk Assessment: 

Various medical models.

Hazard Risk Likelihood Severity Overall Mitigation Likelihood Severity Overall
Small parts Small parts could be swallowed. 2 2 4 Do not let children play with experiments unattended. Call first aider in case of ingestion and encourage the child to cough. 1 2 2
Broken parts If broken, parts could be sharp. 2 2 4 Remove broken models. Call first aider in case of injury. 1 2 2
Pointed parts Some parts have fairly sharp points - risk to eyes/skin. 3 2 6 Sharp points filed down to be as safe as reasonably possible. Call a first aider in case of injury. 2 2 4

Note the functional ear model is only filled with a few mLs of water and is not a risk if it bursts.