People were quick to offer suggestions over what might be causing the sound to appear.
Professor of acoustic engineering Trevor Cox said synaesthesia was the correct explanation for people hearing the sound.
"There are well known cases of sensory inputs crossing to other domains, eg people who associate colours with sounds," he told Alphr.
"So it doesn't surprise me that for some viewers a sound results.
"We also tend to think of our senses as being separate, but our brain collates responses from all senses to work out what is going on. So I would say it is likely to be some effect in the brain rather than a physical effect like the acoustic reflex."
Professor Julia Simner, of the University of Sussex, agrees.
"Those who hear it are experiencing vision-sound synaesthesia," she said.
"Synaesthesia is a trait that affects a small percentage of the population and gives rise to unusual additional perceptual experiences. In vision-sound synaesthesia, the visual movements (often something pulsing, or moving rhythmically) can trigger sound associations.
"I don't have synaesthesia so don't hear anything, but I notice that this looks to be a particularly good trigger. It has all the elements needed — something repeating … and something that would in fact make a loud noise in real life — so I'm not surprised that many people have been hearing it."
