Tap a drum, pluck a guitar string, or ring a bell. Every sound you hear starts with something wobbling to and fro. That tiny wobble is called a vibration.
Sound comes from vibrations
A vibration is a fast back-and-forth movement. When you hit a drum, the skin on top wobbles very fast — that wobble makes the sound. Put your fingers gently on your throat and hum, and you can feel it buzzing. That is your voice vibrating!
How sound reaches your ears
The vibrations make the air around them wobble too. This wobble travels through the air to your ears, making a tiny part inside wobble, and your brain hears a sound. Sound needs something to travel through, like air or water — in space, where there is no air, there is no sound at all.
Louder and quieter
How hard you make something vibrate changes how loud it is.
| Vibration | Sound |
|---|---|
| Big vibration (hit the drum hard) | Louder |
| Small vibration (tap the drum gently) | Quieter |
Higher and lower (pitch)
Pitch means how high or low a sound is. A fast vibration makes a high sound, like a whistle. A slow vibration makes a low sound, like a big drum. A short, thin string vibrates fast and sounds high; a long, thick string vibrates slowly and sounds low.
Sound fades with distance
The further sound travels, the fainter (quieter) it gets. If your friend calls you from across the park, their voice sounds soft; up close, it sounds loud. That is why we cannot hear a whisper from far away.