An audio snippet with just two syllables has ignited an internet meltdown, dividing social media users into staunchly opposed camps: do you hear "Yanny" or "Laurel?" 

The collective sensory experiment causing a Twitter tizzy mushroomed from a short audio clip originally published by a high school student on Reddit.

Roland Szabo, 18, said he recorded the seemingly innocuous audio from a vocabulary website while doing a project for his school in the US state of Georgia.

He played it for his peers, who disagreed over whether the syllables formed "Yanny" or "Laurel."

Intrigued, Szabo sent it to a friend who posted the clip on Instagram and created a poll that quickly went viral, triggering a mass debate that has spread internationally.

Input from celebrities has inflamed the frenzy: "It's Yanny," horror writer Stephen King said in a deadpan tweet.

"It's so clearly laurel," said supermodel Chrissy Teigen. "I can't figure out how one would hear yanny."

In perhaps the most vexing element of the debate, the majority of listeners hear beyond doubt one of the two words, with few waffling between the two.

The controversy recalls the similarly impassioned debate that broke out over the #TheDress.

In 2015, a photo of a two-toned frock had social media users tearing their hair out over whether its colours were white and gold, or black and blue.