| Sound |
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In order to produce a sound something has to vibrate.
The vibrating object causes sound waves in the air which make the ear drum in our ear vibrate.
There are two things that can change how you hear a sound
The speed of the vibrations decides the pitch of the note: Faster vibrations produce a note with a higher pitch.
The size of the vibrations decides the volume of the sound: If the size increases then the sound will get louder.
| The diagram shows a vibrating string. The string can be made to vibrate with a higher note 3 ways: 1. Make the string tighter |
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The speed of sound
Sound travels much slower than light.
This is why we see the flash of a gun before we hear the sound
Sound travels faster in solids and liquids than it does in air.
Sound will NOT travel through a vacuum.
How sound is produced in different musical instruments
instrument part which vibrates instrument part which vibrates
Echoes
An echo is heard when sound is reflected off a distant object.
Sonar make use of echoes to measure the distance (or shape) of an object (eg the sea floor).
It does this by measuring the length of time it takes to hear the echo.
Ultrasound
Ultra sound is too high for us to hear.
It can be used to produce pictures of unborn babies,
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Some waveforms
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These vibrations are large which makes it a loud note. They are quite far apart so that means it sounds low. |
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These vibrations are close together so they must be vibrating fast. This makes it a high note |
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When the vibrations are small the note must be quiet. |
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We can see here that the vibrations gradually fade away. This means that the note starts off load and then gets soft. |
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The squiggles in this note give the note a richer, more interesting sound. |
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