The viral “Laurel or Yanny” meme is quickly becoming 2018’s version of the Dress Illusion, but there’s one big difference: Some people can hear both. Posted to Twitter on Monday, the clip features a single two-syllable word, which initially divided people into Team Laurel or Team Yanny but eventually rooted out some folks that could hear both, if they listened hard enough. (The Dress didn’t allow for such interlopers.) There’s one very compelling linguistic theory explaining why some people have their foot in both camps.

Rory Turnbull, Ph.D., an assistant professor of linguistics at the University of Hawai‘i at Mānoa, explains to Inverse that it all comes down to how a person perceives the frequencies that make up the word. A brief primer on hearing: “Most speech sounds are composed of multiple different frequencies at the same time,” he says. “In most sounds, there are three main frequencies.” The problem with this clip, he explains, is that some people tend to hear certain frequencies and ignore others, despite the fact that they’re all there.

Here’s the graph you get when you run a frequency analysis on the clip. The dark parts show low-intensity frequencies (the ones you don’t hear as well), and the orange and yellow parts show high-intensity frequencies (the ones that stand out). What divides people into Team Laurel, Team Yanny, and Team ‘I Can Hear Both’ is how their ears and brains parse the orange and yellow parts.

yanny laurel frequency analysis
In this frequency analysis, darker areas show low-intensity frequencies and orange and yellow areas show high-intensity frequencies.

Team Laurel

“What I think is going on in this case is that for the word “Laurel,” in the very first vowel in that word, the first two frequencies which are important in that word are generally very close together,” says Turnbull. You can see this “frequency bundle” below, near the bottom of the graph; for a male speaker, says Turnbull, they’re probably in the 500-700 Hz range. Since they’re so hard to tease apart, visually and acoustically, some people will perceive it to be a single smooshed-together frequency, while others will hear both.

yanny laurel frequency analysis
If you hear two frequencies in this area, you're probably going to hear "Laurel.'

“If you’re running with the interpretation that ‘Here are two frequencies that are smooshed together’, this sounds like an ah,” says Turnbull. “So this is probably the word Laurel. And then later on in the sound, there’s a third frequency that sort of dips down. A dipping third frequency is very commonly what we hear when we hear an er sound.”

“If you look at it from that perspective, all of the frequencies in there are consistent with it being Laurel.” For the record, it’s actually “Laurel”: The meme is from the voice recording on Vocabulary.com.

Team Yanny

But Turnbull said it himself: It’s all about perspective. If you perceive a different subset of frequencies in that first frequency bundle, then you’re going to hear something else. Members of Team Yanny, he says, are likely perceiving that smooshed-together bundle as a single frequency rather than two, which leads to their very different interpretation.

“If we go back to the start and think, ‘Okay, I hear this low frequency which is kind of smooshed out wide, and we think this is one frequency — it’s not two that are really close together — then what’s the second frequency in this sound?’” Let’s take another look at the graph.

yanny laurel
If you take into account these high frequencies, you'll probably hear Yanny.

“So we look up and we find out that there’s another frequency, way way higher, around 2,500 Hz or maybe a bit higher than that.” That makes for a very different combination of frequencies, when combined with the low smooshed-together bundle below. “If you have a very high second frequency and a relatively low frequency, that sound like a yuh.”

In other words, what you hear depends on whether you’re paying attention to only the low-frequency sounds (Laurel) or to the high-frequency sounds as well (Yanny). “It’s like a conspiracy, almost, of how these frequencies are playing themselves,” says Turnbull.

Team ‘I Can Do Both’

The thing to remember is that all the frequencies are in the clip. You might hear more low or high ones depending on the type of speakers you’re using to listen to it, but ultimately it’s your brain that’s ignoring certain frequencies and tuning into others.

In the case of the people who hear “Laurel” — the ones who perceive the low-frequency bundle as two frequencies, creating the ah sound — they are still hearing that 2,500-Hz frequency that creates the yuh sound, but they’re just ignoring it. Turnbull thinks they do this because, by focusing on that low ah, they are likely assuming that it was made by a male speaker with a relatively low pitch range. Men don’t usually make sounds in the 2,500 Hz range. “So, for that type of speaker, the second frequency being that high is impossible, so it’s probably some other type of sound going on there.”

But some people are able to change the frequencies that their brains focus on. You can do this my manipulating the sound file itself: A lot of people have noted that increasing the bass or changing the speed of the clip will allow them to hear the word they hadn’t heard before. But for a lot of other people, it’s still not enough. “I think that’s because some people are just very extreme with their method of perception,” says Turnbull.

Others will suddenly be able to hear the new word once it’s been pointed out to them. A person’s ability to do this has to do with how their brains “fill in” sounds perceived as “missing” in order to make sense of what they’re perceiving. Some people seem predisposed to go with only what they hear, while others seem to be predisposed to filling in the gaps. “And a lot of people seem to be sort of in the middle,” says Turnbull. If you can hear both, he’s talking about you.