A viral video that recently resurfaced on TikTok has social media users debating once again — just what am I hearing?

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Two years after “yanny” and “laurel,” took the internet by storm, here’s a new viral video confusing listeners.

The video, which first hit the internet in 2018, but has since seen new life after recently going viral on TikTok, features a voice saying either “brainstorm” or “green needle.” The noise one hears seems to change depending on which phrase the listener is reading or thinking about at the time.

The clip has now gone viral, with more than 7.5 million views and nearly 500,000 likes on the popular social media app, leaving listeners perplexed.

"I've watched this 127 times and now I'm stuck on brainstorm," one user commented.

Added another, "That's absolutely baffled my head."

The mind-bending sound first gained traction online in 2018, and involves a toy from the children's television show Ben 10 Alien Force.

At the time, the original creator of the video told The Telegraph that the toy is programmed to say “Brainstorm," the name of a character in the show, though it can be heard as “green needle" if one is thinking those words.

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"The effect seems to work as follows: When you ‘think’ green needle you hear that word, but when you ‘think’ brainstorm, you hear the other," Valerie Hazan, a professor of speech sciences at University College London, told the outlet in 2018.

“Basically, you are priming your brain to expect acoustic patterns that match expected patterns for a particular word,” she added. “When faced with an acoustic signal which is somewhat ambiguous because it is low-quality or noisy, your brain attempts a ‘best fit’ between what is heard and the expected word."