Being able to hear what you see sounds like a superpower, in the ranks of X-ray vision or telepathy. But it's not quite as far-fetched — some people really can hear silent moving images. In fact, a study published in the June 2018 issue of the journal Cortex shows that up to 1 in 5 people could have the ability.
Visual-evoked auditory response, or vEAR, is the involuntary and consistent experience of having an "auditory sensation [that] occurs in time with visual change over time, caused by motion of sudden flashes," as the study authors define it. In other words, certain silent but dynamic videos and GIFs, like the ones below, trigger imaginary noises in people with vEAR.
Previous research has shown that the phenomenon is a form of synesthesia, where the stimulation of one sensory or cognitive pathway automatically provokes the stimulation of another. For instance, people with chromesthesia, or sound-to-color synesthesia, perceive specific color associations when listening to music. But overall, little is known about vEAR. So the researchers at City, University of London aimed to learn more about its prevalence, the kinds of videos that prompt it and the traits that may predict a person's susceptibility to it.
To do this, they created an online survey that presented 24 short, silent videos to participants mainly from North America, Western Europe and the United Kingdom. Some videos depicted straightforward motion, like a person screaming or a tennis ball bouncing on a racket, while others were more abstract, like twinkling dots colliding with each other. After watching each video, participants were asked to rate whether they'd experienced any auditory sensation on a scale from zero to five, with five representing "very vivid and definite auditory sensation." Of the 4,128 people who completed the survey, 1,058 also answered questions about their traits, including "Do you suffer from tinnitus?" and "Do you ever hear music in your head?"
The researchers found that a surprising number of respondents — 12 percent — identified as synesthetes, and 21 percent were "previously aware of experiencing auditory sensations accompanying visual movement." Considering only 2 to 4 percent of the population reportedly are synesthetes, these numbers are unusually high. This might be because connections between sound and visual events are found more in nature than other synesthetic associations, such as the relation of numbers and letters with colors. The study authors also discovered that the people who were previously aware of experiencing vEAR were more likely to say they had tinnitus, saw sound-evoked flashes of light when in the dark or falling asleep, heard music in their head and experienced synesthetic associations.
Participants identified the most auditory sensation when viewing silent videos that suggested real-world sounds, like a person screaming. But abstract videos with high motion energy, like swirling lights, also evoked sound responses in people who were already aware of vEAR. These results suggest that vEAR could be a form of cognitive association, triggered when viewing a familiar event that we expect to produce a certain sound. But it could also be a true form of synesthesia that doesn't depend on the brain making familiar audiovisual connections.
"We think that these sensations may sometimes reflect leakage of information from visual parts of the brain into areas that are more usually devoted to hearing," said Dr. Elliot Freeman in a press release.
The high prevalence of vEAR opens up more avenues for researching synesthesia and related phenomena. But until then, there's a whole Reddit forum you can peruse to see if you've got a "visual ear" — just try not to get lost in the noise.