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Sound

Soun with Mike the Mic

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HOMELearning Links > Science > Sound

Pass it along

Because sounds are made when objects vibrate, there must be a material for there to be sound.

Sound cannot travel through a vaccuum because there is nothing to pass along the vibrations.


scream_in_space.pngIn space, no one can hear you scream -  because there is no air to pass along the sound vibrations.

If two astronauts want to talk to each other in space, they have to use a radio, or get their helmets touching together and shout.


A dense material like wood allows sound waves to pass very well; this is why a lot of musical instruments are made of wood, or have wooden sound-boxes. Try banging a metal fork on a wooden table and listening to the sound pass through the wood.

listening_to_table.png

You should be able to hear a tone from the vibrating fork, passing through the table to your ear.


fork_head.pngYou can also try holding a vibrating fork on your head. Sound travels very well through bone, and you might be surprised at how loudly you can hear the fork.

Sound also travels through water. Wales use this fact when they sing to each other. Sound actually travels more than 4 times faster through water than through air.

String Telephone


Mike_stringtelephone.pngYou can make a string telephone to see how sound travels through solid materials. All you need are two plastic cups and a length of string.

Drill a small hole in the bottom of each plastic cup, and thread through the string. Fix the string in place by tying a knot or using glue.

Give one cup to a friend and stretch the string tight between you. If the string is floppy, the sound will not pass. If you pull too tight, the string will pull out from the cup, and you will have to start again!

Get your partner to talk to you through their cup, wile you listen at your cup. The sounds should travel along the string from cup to cup, as long as the string is tight.

Sound in Jelly?

Does sound travel through jelly? We did an experiment to see if soundwaves will travel through strawberry jelly.

We used a signal generator to make a sound, and connected this to a small waterproof speaker. We put this speaker into a lump of jelly.

jelly_experiment.pngAt the other end of the jelly we placed a waterproof microphone, and connected this to the microphone port of a PC. The PC was running some oscilloscope software to show whatever the microphone recieved.
We saw a soundwave on the oscilloscope which must have passed through the jelly.
We found that sound was detected up to a thickness of 10cm of jelly.

Now we know sound travels through all sorts of materials. Some better than others.

The poor conductors of sound are Sound Insulators. We could use these materials to block or muffle sounds.


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webmaster@crockhamhill.kent.sch.uk 

Crockham Hill C.E. Primary School. Edenbridge, Kent. TN8 6RP.
Tel. 01732 866374

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