How Different Materials Affect Sound Waves: 10 Fun Experiments for Kids
Educational and Fun Activities
Written by Charlotte Wilson
8 January 2025
🕓 12 min
Sound and the World Around Us
Have you ever noticed how your voice sounds different when you speak in an empty room compared to a carpeted one? Or wondered why sounds are muffled when you cover your ears? These everyday observations provide a fascinating glimpse into how different materials affect sound waves. Sound behaves differently depending on the medium it travels through, and by understanding these interactions, children can gain a deeper appreciation for the world of sound.
At The Science of Sound, we believe in making science fun and accessible for kids through hands-on learning. In this blog post, we’ll explore how different materials influence sound waves, and we’ll share 10 engaging experiments that allow children to see (and hear!) these effects in action.
A. What Are Sound Waves?
Sound waves are a type of energy that travels through a medium—air, water, or solids—in the form of vibrations. These vibrations move outward from the source, creating waves that our ears interpret as sound. The speed and behavior of sound waves vary depending on the properties of the material they’re traveling through.
In air, sound travels at about 343 meters per second.
In water, sound travels faster—about 1,500 meters per second—because the particles are closer together, allowing the vibrations to move more efficiently.
In solids, sound can travel even faster, depending on the density and elasticity of the material.
10 Fun Experiments to Explore How Materials Affect Sound Waves!
1. Soundproofing Challenge
Objective: Teach kids how different materials absorb sound.
Materials Needed:
- A ticking clock or a phone playing music
- Cardboard box
- Various materials (cotton, bubble wrap, fabric, aluminium foil, sponge)
Steps:
- Place the ticking clock or phone inside the cardboard box.
- Cover the box with one type of material and listen to how the sound changes.
- Repeat the process with different materials and note which ones absorb the sound best.
Explanation:
Soft, porous materials like cotton and sponge absorb sound waves, reducing the amount of sound that escapes. Hard materials, like aluminium foil, reflect sound waves, allowing more sound to escape.
2. Water vs. Air: How Does Sound Travel?
Objective: Compare how sound travels through water and air.
Materials Needed:
- A clear bowl of water
- A metal spoon
- A friend or family member
Steps:
- Tap the metal spoon against the side of the bowl while it’s filled with air and listen to the sound.
- Now fill the bowl with water and tap the spoon again.
- Discuss how the sound changes when the medium is water instead of air.
Explanation:
Sound travels faster in water because the particles are more tightly packed, allowing vibrations to move more efficiently. This is why sounds underwater often seem clearer or louder.
3. String Telephone
Objective: Demonstrate how sound travels through solids.
Materials Needed:
- Two paper cups
- A long piece of string (about 2-3 meters)
Steps:
- Poke a small hole in the bottom of each paper cup.
- Thread the string through the holes and tie knots to secure it.
- Have two participants hold the cups tightly by the rims while keeping the string taut.
- One person speaks into one cup while the other listens through the other.
Explanation:
The sound waves created by speaking into the cup cause the string to vibrate. These vibrations travel along the string to the other cup, where they are converted back into sound waves that the listener can hear.
4. Echo in a Tunnel
Objective: Help kids understand how hard surfaces reflect sound to create echoes.
Materials Needed:
- A large, empty room or a tunnel
Steps:
- Stand at one end of the tunnel or room and clap your hands.
- Listen for the echo as the sound bounces back from the walls.
- Move closer to the walls and clap again to observe how the echo changes.
Explanation:
Hard surfaces reflect sound waves, causing them to bounce back and create an echo. Softer surfaces, like carpet or curtains, absorb sound, reducing echoes.
5. DIY Sound Waves with a Rubber Band Guitar
Objective: Explore how tension and material thickness affect pitch.
Materials Needed:
- A small box (like a tissue box)
- Rubber bands of different thicknesses
Steps:
- Stretch different rubber bands around the box.
- Pluck each rubber band and observe the pitch.
- Try tightening or loosening the rubber bands and note how the sound changes.
Explanation:
The pitch of the sound depends on the frequency of the vibrations. Thicker rubber bands and lower tension produce lower-pitched sounds, while thinner rubber bands and higher tension produce higher-pitched sounds.
6. Balloon Vibration Experiment
Objective: Show how sound waves cause vibrations.
Materials Needed:
- A balloon
- A speaker or phone playing music
Steps:
- Inflate a balloon and tie it off.
- Hold the balloon close to a speaker playing music with a strong bass.
- Ask kids to place their hands on the balloon and feel the vibrations.
Explanation:
Sound waves from the speaker cause the air inside the balloon to vibrate, which can be felt as movement on the balloon’s surface.
7. Singing Glasses
Objective: Teach kids about resonance and how different materials produce sound.
Materials Needed:
- Several identical glasses
- Water
Steps:
- Fill the glasses with different amounts of water.
- Gently rub the rim of each glass with a wet finger and listen to the sound it produces.
- Compare the pitch of the sound produced by each glass.
Explanation:
The sound is produced by the vibration of the glass. The amount of water changes the frequency of the vibration, altering the pitch.
8. Sound Reflection with Aluminium Foil
Objective: Explore how reflective materials affect sound waves.
Materials Needed:
- Aluminium foil
- A ticking clock or phone
Steps:
- Wrap the clock or phone in aluminium foil and listen to how the sound changes.
- Remove the foil and compare the difference.
Explanation:
Aluminium foil reflects sound waves, making the ticking sound louder because more sound waves are directed outward.
9. Whisper Tubes
Objective: Demonstrate how sound waves travel through curved pathways.
Materials Needed:
- Two paper towel tubes
- A curved plastic tube (like a garden hose)
Steps:
- Speak into one end of the paper towel tube while a friend listens at the other.
- Try the same with the curved plastic tube and compare how the sound travels.
Explanation:
Sound waves can travel along curved paths as long as they have a medium to move through. The rigid walls of the tube help guide the sound waves.
10. Comparing Sound in Different Solids
Objective: Investigate how sound travels through different types of solids.
Materials Needed:
- A metal rod
- A wooden dowel
- A plastic tube
Steps:
- Tap each solid with a spoon and listen to the sound it produces.
- Compare the volume and pitch of the sound produced by each material.
Explanation:
Sound travels differently through various solids depending on their density and elasticity. Denser materials like metal allow sound to travel faster, producing a louder sound.
Conclusion:
Engaging Kids in the Science of Sound
Exploring how different materials affect sound waves is a fun, hands-on way to introduce kids to physics and the science of sound. By conducting these simple experiments, children can better understand concepts like vibration, pitch, and resonance in a way that’s engaging and memorable.
At The Science of Sound, we offer workshops and activities designed to make learning about sound fun and interactive. If your kids enjoyed these experiments, check out our upcoming programs to learn more! Contact us today to find out how you can be part of the borough’s exciting future!
