It's rare for people to disagree on the internet, but no amount of civility could be spared when a "social media influencer" named Cloe Feldman posted a four-second sound clip on Twitter on May 15, 2018 and asked followers whether they heard a voice say "Yanny" or "Laurel."

Maybe you hear "Yanny." Maybe "Laurel." Proponents of either one recognize a very distinct word, which seems like some kind of aural magic trick. 

Popular Science asked several audiologists to help explain what’s going on. Brad Story, a professor of speech, language, and hearing sciences at the University of Arizona, performed a waveform analysis, which is already more effort directed at this than at the ransom calls for the Lindbergh baby. Story observed that the recording's waveform displays the acoustic features of the "l" and "r" sounds, offering reasonable proof that the voice is saying "Laurel." Whoever engineered the track seems to have layered a second, higher-frequency artifact over it—a frequency that sounds like "Yanny" to some people.

But why do listeners hear one name versus the other? We listen with our brains, and our brains tend to prioritize certain sounds over others. You might be focused on hearing your child talk, for example, over the din of a television. Because "Laurel" and "Yanny" are on different frequencies, some listeners are subconsciously favoring one over the other.

Audiologist Doug Johnson of Doug Johnson Productions provided further proof in his YouTube video analyzing the recording. By isolating each track, it's clear listeners can hear both "Yanny" and "Laurel."

A bigger mystery remains: Who conceived of this recording? It wasn't Feldman, who said she picked it up from a Reddit conversation. According to Wired, the answer is likely Georgia-based high school freshman Katie Hazel, who was looking up the word "laurel" on Vocabulary.com, had the site play it back, and was confused when she heard "Yanny" instead. She shared the discrepancy on Instagram, which was picked up by school senior Fernando Castro. From Castro's Instagram, it landed on Reddit. The original recording was performed for Vocabulary.com in 2007 by an unnamed opera singer and former cast member of the Broadway musical CATS.

Vocabulary.com isn't sure if the singer will come forward to claim their role in this fleeting internet sensation. In the meantime, the "Yanny" and "Laurel" camps continue to feud, mystified by the inability to hear what the other can. Musician Yanni is in the former group.

[h/t Popular Science]