"Why some people can hear this silent gif"

"He suggested a possible theory which his lab call the "visual ear."

"I suspect the noisy gif phenomenon is closely related to what we call the Visually-Evoked Auditory Response, or vEAR for short," explained Fassnidge.

"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."

http://www.bbc.com/news/science-environment-42237092?utm_content=64056471&utm_medium=social&utm_source=facebook

I am constantly "hearing" silent things. Like, when you mute a TV show or movie but your brain fills in some of the sounds and the cadence of the dialogue. It's probably not quite right, but I've never figured out a way to compare.