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A Comprehensive Guide to Homeschooling

How sounds travel


How does sound travel?

Sound travels in a wavy (curly or curvy) way.


What are sound waves?

The way sounds travel through air, solids or liquids.

Sound waves
(The way that sound travels)


Now we know the way how we can hear sounds.


When something vibrates, sound waves are made and they move the air around them and make the air vibrate. These air vibrations enter our ears which we hear as sound.

E.g. –

1) If you ring a bell, the bell vibrates and makes sound waves. These sound waves make the air around them vibrate too and we can hear the bell is ringing.  


2) Following picture shows us the way that we can hear the sound of a horn.



Features of sound waves

  1. Sound travels in a wavy way.
  2. When sound travels very far it becomes weaker. (The further sound waves travel, the weaker they become)


E.g. – You can clearly hear the rumble (a loud continuous noise) of a train when it travels near by, but when it travels further, little by little the sound decreases and cannot be heard clearly. That is why we cannot hear a distant sound.


Different types of sound waves


Tuning Fork








Thunder and lightning


Can you name one of the loudest sounds we hear?  Thunder


What is thunder?

Thunder is the loud sound made by lightning. Thunder sounds like an explosion. Lightning causes thunder.


What is lightning?

Lightning is a huge electric spark.





We can hear We can see
Slower than the speed of light Faster than the speed of sound



In a storm, why we often hear the thunder after we see the flash of lightning that made it?

The speed of light is faster than the speed of sound. Therefore in a storm we often see the thunder after we see the flash of lightning.


Travelling through air, solids and liquids


  • Sounds can travel well through gases such as sir.
  • Sounds can travel faster through liquids such as water.
  • Sounds can travel best of all through solids such as metal, stone, glass, brick and wood.


What is the fastest medium through which sound can travel?


E.g. – 1) Sounds travel very well along metal pipes.

         2) Sounds travel better through solid ground than through the air.



Underwater sounds


Sounds can be heard well underwater. 

E.g. – 1) A diver can hear the engines of a boat before someone on the surface can.

            2) Whales use sounds called, ‘songs’ to communicate with each other. These whale songs carry many hundreds of kilometres underwater. 



Hearing and space


What is a vacuum?

A vacuum is a completely empty space. It has nothing, not even air in it.


Can sounds travel through a completely empty space or a vacuum?

No, they cannot. Sounds cannot travel through a completely empty space or a vacuum.


If there is a vacuum between a sound-making object and our ears, we won’t be able to hear the sound.

E.g. – 1) On the moon there is no air. You could talk to people right next to you and they wouldn’t be able to hear you.

2) If you want to talk to someone in space, you have to change sound vibrations to electrical or radio signals.