Vibration, sound and hearing (continue) - Worksheet Gr 4

You have learned that musical instruments make sounds through vibration.

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Vibrations and sound

Put your finger on your throat and sing or talk.  Do you feel the vibration? It is this vibration that causes the sound when you sing or talk.

But what causes the vibration in your throat?  We all have vocal cords in our throat, so when the air moves over it, it vibrates and causes sound.

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So, we make sounds when our vocal cords vibrate, but how do we hear sounds?

In your ear you have eardrums.  When the sound goes into the ear, the eardrum vibrates and this is how you hear sound.

Your ear is made up of different parts.  You have an outer ear on the outside of your head and on the inside of your head you have different small bones and your eardrum.  The vibration of the eardrum bumps the little bones next to it and the brain can then read this as a sound.

Watch the video explaining how you hear

Vibrations travel through a material

Sound needs something to travel through.  If you listen to your friends speak, it is because the sound travels through the air.  If you put your ear against a wall and you can hear sounds on the other side, it is because the sound travels through the wall .

                           

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Sound can travel through different types of solids, but it can also travel through liquid and gas.

Can you give examples of solids, liquids and gasses?

 The medium your voice travel through is air.

• If you are in a vacuum (a place filled with no air or any type of matter), will you be able to hear sound?  Why do you say this?

Noise pollution

There are many kinds of pollution, like rubbish and waste lying around, or in the water or even in the air.  

• Look at the following pictures and describe what you see and what type of pollution it is and what do you think is the effect on the environment.

        

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There are other types of pollution as well and one of them is called noise pollution.

                              

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• Can you think of any other things that can cause noise pollution?

Noise pollution can be very unpleasant and it can also cause damage to our hearing.

Although we cannot always avoid noice, if you are in an area, like a factory, with a lot of noise you must take care of your ears by wearing protective gear.

                     

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You must also be careful to listen to very loud music, especially through ear phones. Too much loud music can cause hearing loss.

Animals can also be harmed or influenced by noise pollution.  Let's think about a whale.  They communicate with each other by making sounds that can travel over long distances through water.  When there are a lots of ships making a noise, it will make it difficult for the whales to communicate with each other and this can cause a whale to get lost in the ocean.

• Why do you think this racehorse's ears are covered?

                   

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If you understand all the work you may watch the video for extra information - you can make notes while watching the video and also create some of your own questions