What do you hear when you watch this GIF? If you hear a loud boom each time the tower lands, you’re not alone… But it is actually a silent GIF, without any sound. The GIF shows three towers playing jump rope. Each time the middle tower lands, the entire image shakes as though the tower were crashing down onto the ground. And even though the image isn’t accompanied by any sound, many people report hearing a loud boom each time the legs of the tower land on the ground.
So, why do some people hear a sound when the tower crashes onto the ground?
The phenomenon may be explained by a condition called synesthesia. The condition causes different senses to be “mixed.” For example, a person with synesthesia may taste sounds or hear colors. But another form of synesthesia, “hearing-motion” synesthesia, could explain “hearing” the GIF. Here again:
Does anyone in visual perception know why you can hear this gif? pic.twitter.com/mcT22Lzfkp
— 𝙻𝚒𝚜𝚊 𝙳𝚎𝙱𝚛𝚞𝚒𝚗𝚎 🏳️🌈 (@lisadebruine) December 2, 2017
The GIF seems to be causing some kind of cross-modality cognitive effect, meaning that people’s brains are internally combining vision with the perception of sound.
In a follow-up tweet, DeBruine added a poll asking her followers what they could hear.
What do you experience when you watch this gif?
— 𝙻𝚒𝚜𝚊 𝙳𝚎𝙱𝚛𝚞𝚒𝚗𝚎 🏳️🌈 (@lisadebruine) December 3, 2017
This illusion of sound may be more common because people are constantly surrounded by a noisy world, and they’ve come to expect that certain sounds will accompany certain visuals, like a clapping hand. So because people have come to expect that a large structure slamming into the ground hard enough to make the ground shake would be accompanied by a loud boom, the brain fills in the missing sensation.