A viral meme generally referred to as “Yanny versus Laurel” has become 2018’s version of the internet-dividing Dress Illusion, only for your ears. It parted Twitter like the Red Sea on Tuesday after the four-second audio clip was posted by user Cloe Feldman: On one side were people who hear “Yanny,” and on the other, “Laurel.” Just as it was with the Dress, reconciliation seems to be impossible. Differences in our ability to perceive audio won’t let it happen.

It’s a maddening clip. “Yanny” and “Laurel,” spoken out loud, sound nothing like one another, and yet somehow a single sound bite can be interpreted, with conviction, as either one or the other. According to Rory Turnbull, Ph.D., an assistant professor of linguistics at the University of Hawai‘i at Mānoa, it comes down to differences in the speakers we’re using to listen to the clip as well as cognitive differences, which fundamentally change the way any one person perceives the sounds. Take a listen for yourself:

In a series of tweets, Turnbull explained in great linguistic detail that differences in how people interpret the sound come down to differences in the way they hear the frequencies that make up the sound. First, a very brief refresher on the physics of sound: Every sound we hear travels in waves, and the frequency of those waves determines the pitch that we hear.

Part of how we hear this meme, as mentioned, is due to the way the sound is played through certain speakers. The “Laurel” interpretation, as Turnbull explained in a tweet, has higher frequencies than the “Yanny” interpretation, and so speakers that increase or decrease certain frequencies might lead listeners to perceive one or the other. However, there’s only so much we can blame on our external hardware; it also comes down to what Turnbull calls the “cognitive dimension.”

By this, he’s referring to differences in the way that people mentally “fill in” sounds that they don’t necessarily perceive with their ears. He thinks that listeners in this situation can roughly (more on this shortly) be divided into two categories named for linguistics terms — “spectral listeners” and “f0 listeners” — describing types of people who naturally fill in the missing sounds in different ways.

Of course, there are always exceptions to nature’s rules: Some contrarians on Twitter have admitted to being able to hear both Yanny and Laurel. There’s likely a separate psychological element involved, as well — here at the Inverse office (where we are very much divided), some people started hearing one name but couldn’t un-hear the other, once it was pointed out to them. Like all good viral memes, this one has successfully driven us mad.