An audio clip that can be heard as two different words has left social media users astounded.
The sound, which first went viral in 2018 and has now resurfaced on TikTok, can be heard as either the phrase ‘green needle’ or the word ‘brainstorm’.
The clip is played while both words are flashed up on screen. The one the individual hears is said to change depending on which word is being read on screen and therefore being thought about.
It was posted in a clip by Emily Sophie, thought to be based in Wales, earlier this week and has since been liked more than 112,000 times, as well as being shared widely across Twitter.
Listeners said they were baffled by the trick, which asks them to think of one of the words before the audio seemingly changes to reflect their choice.
In her clip, Emily asks viewers to listen to the same audio twice, once while looking at a caption reading ‘brainstorm’ and again while looking at the word ‘green needle’.
‘You will only hear the word you’re reading,’ her third caption suggests.
Shocked by the illusion, one person wrote: ‘Tried a few times. Was blown away until I read green needle but heard brainstorm. So now I don’t know if I’m too clever for it or what. You?’
Another said: ‘It’s got me questioning how I interpret almost anything that people say to me, do I just hear what I want to hear?’
A third individual added: ‘You can also get it to say “brain needle” too. This is messed-up.’
The clip even attracted the attention of several well-known faces including actor and comedian Ricky Gervais, who retweeted the footage alongside the caption: ‘It also works if you close your eyes and just think of the one you want to hear.’
Despite the widespread puzzlement, this isn’t the first time the audio trick has been shared online.
It appeared in a 2018 Reddit post, with that version showcasing a toy that when activated seemed to say either of the two words.
It was previously confirmed that the audio actually says brainstorm.
Professor Valerie Hazan a speech, hearing and phonetic sciences expert from University College London, told the Huffington Post last year that the reason behind the success of the trick is that our minds can ‘latch on’ to the second perceived acoustic pattern.
‘The reason that a person can see their perception switch without explanation may also mean that our ears and brain have latched on to the other acoustic pattern than the one they were previously latching on to,’ she explained.