How Can Two Sounds Cancel Each Other Out?

What Crafty Clover says in this video

Intro

Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. How can two sounds cancel each other out?

The Big Idea

Two sounds can cancel each other out when their waves are exact opposites! Where one wave goes up, the other goes down. When they meet, they add up to almost nothing.

Listen to Noise

Step one: listen to the noise. Noise-cancelling headphones have tiny microphones that listen to the sounds around you. They measure the noise wave very quickly, many times each second.

Make the Opposite

Step two: make the opposite. The headphones then play a sound wave that is the opposite. Where the noise wave goes up, theirs goes down.

Waves Cancel

Step three: the waves cancel. When the two waves meet, they cancel each other out. That leaves much less sound to reach your ears, so the world seems calmer.

A Closer Look

Let's take a closer look! A tiny microphone hears the outside noise. The headphones make the opposite wave. The two waves add up to almost nothing, like plus one and minus one. You hear much less noise.

Quick Facts

Quick facts! It works best for steady humming sounds like engines. Quick sounds, like a clap, are harder to cancel. The idea is called destructive interference. Keep your volume low, since cancelling noise is not a license to turn it up.

Think Like a Scientist

Now, try this! On a sheet of paper, draw a wiggly wave. Below it, draw the opposite wave, with a hill where the first has a valley. Add up the heights at each point. What do you notice about the up and down parts? Share what you discover with a grown-up.

Outro

Opposite waves can cancel to quiet. Science is amazing! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!