What is sound?

Clap your hands. Bang a drum. Shout your own name! Where do all these sounds come from, and how do they get to your ears? The answer is a tiny, busy wiggle.

Sound starts with a shake

When something makes a sound, it is really shaking very fast. We call that shaking a vibration. Pluck a guitar string and watch it blur — it is vibrating! Touch your throat while you hum, and you can feel it buzzing too.

A wiggle in the air

The shaking thing pushes the air right next to it. That air bumps the air a little further away, which bumps the next bit of air, and on and on. This travelling push is a sound wave, like ripples spreading across a pond.

The wave races through the air until it reaches your ears. Your ears feel the wiggle, and your brain turns it into the sound you know — a clap, a drum, a giggle.

No air, no sound

Here is the clever part: sound needs something to wiggle through. In outer space there is no air at all, so there is nothing to carry the wave. Even a giant explosion would be totally silent up there!

Wonder fact: Sound travels much faster through water than through air. Whales can “talk” to each other across many kilometres of ocean using their booming songs.