ELI5: Explain Like I'm 5

Parseval's theorem

Have you ever heard of a special math rule called Parseval's Theorem? It's like a magic spell that helps us figure out some important things about sound and waves.

Do you know what sound is? When you hear a noise, it's because something is making waves in the air that travel all the way to your ears. These waves have different shapes and sizes, and they can be tall or short, fast or slow.

Now, let's imagine that we have a group of people singing a song together. Each person's voice makes a different wave that adds up to make the whole sound. But if we want to understand what makes up the sound, we need to break it down into its individual waves.

This is where Parseval's Theorem comes in. It tells us that if we add up the squares of all the different waves that make up a sound, we will get the same number as if we added up the squares of the whole sound. It's like saying that the sum of the parts is equal to the sum of the whole.

Now you might be wondering, why is this important? Well, scientists use this theorem all the time to study sound and music. They can analyze the different waves in a song to figure out what instruments were used, how fast the rhythm is, and many other things.

So there you have it, Parseval's Theorem is a special rule that helps us investigate the different waves that make up sound. Pretty cool, huh?