The Doppler Effect is a cool idea that changes how we hear sounds.

When something that makes noise comes closer to us, the sound waves get squished together. This makes the sound higher in pitch.

But when it moves away from us, the sound waves stretch out. This causes the sound to be lower in pitch.

Examples

• Ambulance Sirens: When an ambulance is coming towards you, the siren sounds higher. As it drives away, the sound gets lower.
• Sports Cars: When a fast car zooms by, it makes a different sound as it approaches and then goes away.

Summary

So, the Doppler Effect shows us how the movement of sound sources changes what we hear, especially the pitch of the sound.