Silent GIF: Some people swear they can 'hear' a mysterious thud in this visual

The mystery of the "Pylon Skipping Rope" GIF is back. Social media users are divided in their opinion on the silent GIF that show three animated electricity pylons in a row, with the one in the middle skipping over multiple cables being rolled by the other two as a skipping rope.

Despite having no sound or music accompanying the GIF, many who watched it claim they can hear a thudding sound every time the skipping pylon lands on the ground.

Reality or an illusion? Social media users have varying explanations for the silent loop of the brief video clip, reportedly created in 2008 by a Reddit user, @IamHappyToast. The GIF was created as part of a photoshop challenge on the boards of b3ta.com and has been baffling social media users ever since.

The clip resurfaced last week when Dr Lisa DeBruine from the Institute of Neuroscience & Psychology at the University of Glasgow posted it on Twitter, asking her followers to describe if they experienced any auditory sensation while watching it.

She also listed some options for her followers, asking if they hear a thudding sound, or nothing, or something else.

The doctor received more than 245,000 responses of which 70% claimed that they could hear a sound, the BBC reported. Even people with hearing disabilities and those with lack of visual imagery also reported they were either able to feel the thud or some kind of sound.

"I don't know why some people hear it very clearly, others only feel it, and others perceive nothing at all. Some deaf and hard of hearing people have reported all three perceptions, as have people with aphantasia," DeBruine told the BBC.

"I thought some of the vision scientists I follow would be able to explain it right away, but it seems like there are several plausible explanations and no clear consensus."

Chris Fassnidge, a doctoral candidate in psychology at London's City University saw the Tweet and said that a possible theory could be "visual ear". He has been carrying out research in this field, he noted. "I suspect the noisy gif phenomenon is closely related to what we call the Visually-Evoked Auditory Response, or vEAR for short," Fassnidge explained.

"This is the ability of some people to hear moving objects even though they don't make a sound, which may be a subtle form of synaesthesia — the triggering of one sense by another.

"We are constantly surrounded by movements that make a sound, whether they are footsteps as people walk, lip movements while they talk, a ball bouncing in the playground, or the crash as we drop a glass. There is some evidence to suggest that synaesthetic pairings are, to some extent, learnt during infancy.

"I might assume I am hearing the footsteps of a person walking on the other side of the street, when really the sound exists only in my mind. So this may be a common phenomenon because the sound makes sense, but for that exact reason we may not even know we have this unusual ability until the noisy gif suddenly came along in the last few years," he explained, noting that the experience of vEAR depends on "how our brain is wired".