How do you explain “sound”? Why do we have two ears? Can you hear in space? Dr Naomi Lavelle from Dr How’s Science Wows explains and explores the science of sound with 3 fun and easy sound experiments for kids to try.
Science is all around us — from the air we breathe to everything we can see, smell, touch, taste and hear. Encouraging a love of science can start young, and there are plenty of easy science experiments you can do at home using ordinary household items.
With these three simple sound experiments, your child can learn all about sound — something we don’t always stop to think about.
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Jump to: [What is Sound?](#what-is-sound) · [Why Two Ears?](#two-ears) · [Sound in Space](#space) · [Echolocation](#echolocation) · [3 Sound Experiments](#experiments) · [FAQ](#faq)
What is Sound? {#what-is-sound}
Sound is a type of energy made by vibrations. These sound vibrations move through the air (or other matter) to our ears, and our brain works out what we’re hearing.
Sound vibrations travel as a type of wave that we cannot see. These sound waves need something made of molecules — solid, liquid or gas — to travel through. The molecules carry sound waves by bumping into each other, a bit like dominoes knocking each other over.
Did you know? Sound waves travel through water at nearly one mile (1.6 km) a second — more than four times faster than sound travels through air!
Why Do We Need Two Ears? {#two-ears}
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We need two ears to work out exactly where a noise is coming from. Our brain compares the level of noise reaching each ear and calculates the position of the sound source.
Did you know? During the making of the film Jurassic Park, the director wanted a dramatic effect to signal the arrival of the T. rex. In the film, we see ripples in a glass of water caused by the T. rex’s footsteps — a special effect achieved by someone plucking guitar strings under the dashboard to create the vibration.
Can We Hear in Space? {#space}
Sound waves need molecules to travel through, so as there are next to no molecules in space, there is no sound in space.
Did you know? Thunder is the sound made by lightning. Sound travels through air at a speed of about one mile every five seconds. If you count the seconds between seeing the lightning and hearing the thunder, you can work out roughly how far away the storm is. For example, if you count ten seconds between the lightning and the thunder, the storm is about two miles away.
What is Echolocation? {#echolocation}
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An echo is made when sound waves bounce off a solid object and travel back to your ear. Some mammals use echoes to navigate and find food — this is called echolocation.
Bats use echolocation to fly and hunt at night. They send out high-pitched squeaks and clicks almost constantly. These sounds are called ultrasonic — too high-pitched for humans to hear. A bat can tell from the echoes bouncing back to it where an object is, its size and shape, and whether it’s moving.
Whales and dolphins use echolocation too, but the ultrasonic sounds they make travel through water instead of air.
Did you know? A bat can detect an object as small as a human hair using echolocation!
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3 Fun Sound Experiments to Try at Home {#experiments}
#1. Can You Feel Sound Waves?
You Will Need:
- A balloon
- A radio
What to Do: Blow up the balloon and tie it closed. Turn on the radio to a song with a strong bass line. Hold the balloon between your two hands and hold it close to the speaker. What can you feel? Try a different radio station and see if the vibrations change.
What is Happening? The sound coming from the radio makes the air near it vibrate. The air molecules inside the balloon are squeezed more tightly together, making them vibrate more strongly. We feel these vibrations in our hands.
#2. Can You Make Sound with Bottles?
You Will Need:
- Two identical bottles
- Water
- A spoon
What to Do: Fill one bottle two-thirds full with water and the other one-third full. First, blow across the top of each bottle — which one makes the higher sound? Next, tap each bottle gently with the spoon — which one makes the higher sound now?
What is Happening? Blowing across the top of the bottles makes the air inside vibrate. The bottle with less air makes the higher sound. When you tap the bottles, it’s the water that vibrates — the bottle with less water makes the higher sound. Smaller amounts of air or water vibrate faster, producing a higher sound.
Next Step: For extra fun, line up several bottles with different amounts of water in each and see how many different notes you can create.
#3. Can You Watch Sound Waves Travel?
You Will Need:
- A small empty plastic drinking bottle
- Scissors
- A small piece of plastic (such as a plastic bag)
- An elastic band
- A tea-light candle
- Matches
What to Do: Ask an adult to carefully cut the end off the plastic bottle. Stretch the piece of plastic over the open end and secure it with the elastic band. Ask an adult to light the tea-light and remove the bottle cap. Hold the narrow end of the bottle near the flame, then tap the plastic at the other end. What happens to the flame?
What is Happening? When you tap the plastic, it acts like a drum. The sound waves it creates make the air molecules inside the bottle vibrate, and those vibrating molecules pass the movement along to the air near the flame — blowing it out.
You can watch these sound experiments demonstrated in the video below.
Watch: 3 Fun and Easy Sound Experiments for Kids
Visit Science Wows for more fun science facts and experiments, and follow Dr How on Facebook and Twitter.
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Frequently Asked Questions {#faq}
What is sound, in simple terms for kids?
Sound is energy made by vibrations. These vibrations travel as waves through air, water or solid objects until they reach our ears, and our brain works out what we’re hearing.
Why do we have two ears instead of one?
Two ears let our brain compare how loud a sound is on each side, which helps us work out exactly where the sound is coming from.
Can sound travel in space?
No. Sound waves need molecules to travel through, and space has hardly any molecules, so there is no sound there.
What is echolocation and which animals use it?
Echolocation is using echoes — sound bouncing off objects — to figure out where things are. Bats use it to hunt at night, and whales and dolphins use a similar version underwater.
What everyday items do I need for these sound experiments?
Just things you likely already have at home: a balloon, a radio, two bottles, water, a spoon, a small plastic bottle, a bit of plastic bag, an elastic band and a tea-light candle.
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- 18 Easy Science Experiments Perfect for Preschoolers
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