ACARA v9 CONTENT DESCRIPTION “explore different actions to make sounds and how to make a variety of sounds, and recognise that sound energy causes objects to vibrate”
Builds on noticing the sounds all around us. Now we look at where sounds come from and find that every sound starts with something shaking very fast.
Sounds come from things that wiggle
When you pluck a string, tap a drum or ring a bell, the thing shakes back and forth very fast. That fast shaking is called a vibration. The vibration pushes on the air, and the air carries the sound to our ears. If nothing wiggles, there is no sound.
Pluck the string
A stretched string is quiet when it is still. Pluck it and watch it wiggle back and forth. That wiggle is what makes the sound.
The string is straight and still, so the air around it is quiet and we hear nothing.
Many ways to make a sound
We can make sounds in lots of different ways: by tapping, shaking, blowing or plucking. Each action makes something vibrate, and each one gives its own kind of sound. Try the actions below and listen in your head to the sound each one makes.
Many actions make sounds
We can make sounds in lots of ways. Pick an action and see how it makes a thing vibrate and give its own sound.
Tapping, shaking, blowing and plucking are all different actions, but each one makes something vibrate. A whistle vibrates the air inside it, a drum vibrates its skin, and a guitar vibrates its string. Every vibration gives its own sound.
Loud and soft, high and low
A gentle action makes a small wiggle and a soft sound. A big action makes a big wiggle and a loud sound. The kind of string matters too: a short, tight string wiggles fast for a high sound, and a long, loose string wiggles slowly for a low sound.
Loud and soft
A gentle action makes a small vibration and a soft sound. A big action makes a big vibration and a loud sound.
Tap the string gently and it makes only a little wiggle, so the sound is soft. Hit it harder and the wiggle gets much bigger, so the sound is louder. A bigger vibration always means a louder sound.
High and low
A short, tight string wiggles very fast and gives a high sound. A long, loose string wiggles slowly and gives a low sound.
Make the string short and tight and it shakes very fast, with lots of little wiggles, so you hear a high sound. Make it long and loose and it shakes slowly, with big slow wiggles, so you hear a low sound.
Sound can move other things
Sound is a kind of energy, and it can make other things move. Sprinkle some rice on a drum and bang the drum. The drum skin vibrates, and the shaking skin makes the rice jump up, even though nobody touches it. The sound itself does the work.
Sound makes things jump
Put some rice on a drum. When the drum makes a sound, the skin vibrates and the rice jumps. Sound makes things move.
When the drum is quiet its skin is still, so the rice just sits there. Sound is what makes the rice jump.
Why this matters
Every sound you hear, from a clap to a song to a barking dog, begins with something vibrating. Once you know that sounds come from vibrations, you can make your own sounds, change them from soft to loud or low to high, and understand how instruments and even your own voice work.
Quick self-check
1. What does a string do when you pluck it to make a sound?
2. Which of these is an action that can make a sound?
3. You hit a drum much harder than before. The sound is...
4. A short, tight string makes a high sound. A long, loose string makes a...
5. Why does rice on a drum jump when the drum sounds?