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Skip to 0 minutes and 7 seconds What is sound? Sound like light is a type of energy that is transmitted by waves. Sound is generated as a result of things vibrating. If something is making a sound it will be vibrating, even if you can’t see it. A good way to ‘visualise’ the vibrations is to bang a fork on a table and then hold it against the top of some water. You should see the vibrations moving away from the fork in circles to the edge of the bowl. Sound does not travel in straight lines but travels out in all directions, hence the ripples on the water. Sound does needs something to travel through. It cannot travel through a vacuum.

Skip to 0 minutes and 50 seconds Which is why they say, ‘in space no one can hear you scream!’ When the sound vibrations reach your ear they vibrate your ear drum which in turn vibrates the three tiny bones sitting on your ear drum. These vibrations are then converted by your brain into the sounds you hear. Anything vibrating makes a sound but sometimes we need to be very close to it to hear it. In order to make sounds louder we often need to amplify the sound. This can be done electronically through speakers or naturally through the body of an instrument. For example inside a guitar’s body, when a string is plucked, the air inside the body vibrates and amplifies the sound to make it louder.

Skip to 1 minute and 37 seconds The same is true of blown instruments, where the air vibrates inside the tubular body. A tuba makes a naturally louder sound than a cornet as it is larger and there is more space for the air to vibrate around in it. (There is also more energy going into the tuba as the tubes are longer so you need to blow more.) Sound vibrations travel by compressing the material that is in front of them, whether that is air or something else, liquid or solid. Imagine a slinky that is held at both ends.

Skip to 2 minutes and 10 seconds If one person pushes the slinky forwards towards the other person the coils will compress towards the next set of coils and so on until they reach the end of the slinky. They will then bounce off the end point and return, this is effectively demonstrating an echo. Sound vibrations actually move more efficiently through solids and liquids than through gases. Think of the old western movies when they would put their ear to the railroad tracks to hear if a train was coming. If you think of the arrangement of particles in a solid they are much closer together and therefore pass on their vibration more efficiently, whereas the particles in a gas have to collide with another particle within a much larger area.

Skip to 2 minutes and 57 seconds This is how string telephones are able to transmit your voice along the string, even when you whisper.

Subject knowledge: sound

Anything vibrating makes a sound but sometimes we need to be very close to it to hear it . In order to make sounds louder we often need to amplify the sound. This can be done electronically through speakers or naturally through the body of an instrument.

For example inside a guitar’s body, when a string is plucked, the air inside the guitar body vibrates around the space and amplifies the sound to make it louder. The same is true of blown instruments, where the air vibrates inside the tubular body. A tuba makes a naturally louder sound than a cornet as it is larger and there is more space for the air to vibrate around in it. (There is also more energy going into the tuba as the tubes are longer so you need to blow more.)

Sound vibrations travel by compressing the material that is in front of them, whether that is a gas, liquid or solid. Imagine a slinky that is held at both ends. If one person pushes the slinky forwards towards the other person the coils will compress towards the next set of coils and so on until they reach the end of the slinky. They will then bounce off the end point and return, this is effectively demonstrating an echo.

Sound vibrations actually move more efficiently through solids and liquids than through gases. Think of the old western movies when they would put their ear to the railroad tracks to hear if a train was coming. If you think of the arrangement of particles in a solid they are much closer together and therefore pass on their vibration more efficiently, whereas the particles in a gas have to collide with another particle within a much larger area. This is how string telephones are able to transmit your voice along the string, even when you whisper.

It is important to give children practical, hands-on experience of investigating sound. What sounds can they create? How would they describe the different sounds they are making?

Describe

Choose ONE musical instrument. What is vibrating to create the sound from the instrument?

Add your thoughts in the comment box.

For example, you could choose:

*A stringed instrument e.g. guitar, piano or violin * A woodwind instrument: e.g. flute, clarinet or recorder * A percussion instrument: e.g. drums or xylophone * A brass instruments: e.g. trombone or tuba

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Teaching Primary Science: Physics

National STEM Learning Centre