When you think of visualizing sound, you might think of the iTunes visualizers you used to play with years ago, or perhaps a waveform that shows the volume of a digital audio file comes to mind. The thing is, though, that sound waves are real things that exist in our physical world. We can’t see them, but there’s an indirect way for us to visualize what these waves look like in a way that we can process with our own eyes.

The video above is from 2009, but it resurfaced on Reddit recently, where commenters were quick to clarify the nature of the clip and add context. For instance, it was established that the type of sound wave we’re seeing here is called a “standing wave,” which is a type of wave that appears to vibrate up and down in place because two waves are moving opposite each other in the same medium. It’s like the type of wave you get when you shake a phone cord, if you remember doing that back in the day. Here’s a demonstration:

Also, if you want to get technical, this may not be a true visualization of a sound wave. As one user put it, “It’s sound creating a wave with other materials as a kind of model,” meaning that while the sound is moving the foam pellets in the tube, we don’t see the sound waves themselves. It’s like looking at a tree on a breezy day: you see the leaves moving because of the wind, but you don’t see the wind itself, just its effect.

Regardless of how you see it, the model is still a great way to observe the nature of sound waves and their impact on the environment around them. Have you seen any other cool and informative illustrations of how sound waves function? Share them in the comments below!

Featured image: Kichul/YouTube