Sound is what we hear from vibrations in air.
Pluck a string on a violin or guitar and the string will vibrate very fast. You can see it moving back and forth in a blur. As it vibrates it bangs into the air molecules around it.
The room is full of air. We can’t see it but we can feel it if we wave our hands about or the wind blows.
Air is made up of tiny molecules of gas: oxygen, nitrogen, carbon dioxide and other gases.
The air we breathe is made up of tiny invisible air molecules. One breath is estimated to contain about 25 sextillion (25 followed by 21 zeroes) air molecules.
Image by Freepik
When the string vibrates it pushes against the air molecules around it and they move and jostle with other air molecules. So as the string vibrates back and forth the air molecules around it are forced to vibrate too.
A sound wave of vibrations travels through the air like the ripples on a pond when a stone is dropped into it.
The sound wave reaches our ears and makes our ear drum vibrate.
The ear drum is a tiny membrane just like the surface of a drum.
When the sound wave reaches it, it causes the tiny drum inside your ear to vibrate too.
When your ear drum vibrates it sends signals along nerves into your brain and you hear the sound. Totally amazing when you think about it!
All sound is created in his way, not just music.
For example, when we speak or sing, we push air from our lungs across the vocal cords in our throat making them vibrate to produce sound waves just as if we had plucked a string on a ukulele or buzzed into a cornet mouthpiece.
The pitch of the sound we hear depends on the frequency or speed of the vibrations. The faster the vibrations, the higher the sound; the slower the vibrations, the lower the sound.
Did you know that sound cannot travel through space because there is no air in space and nothing to vibrate? But sound can travel through a wall, the ground or your body!
Find out more about sound on wikipedia
For more details about how our ears work see this article from Nottingham University
Now read our page on Harmonics
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