Why Your Brain Sometimes Hears Sounds That Don't Exist

In May 2018, the internet was abuzz with debate: Laurel or Yanny? Some listeners heard the former name in the viral audio clip, while others were convinced the voice was saying the latter. AsapSCIENCE’s latest video, spotted by Digg, helps explain how aural illusions work, and why hearing isn't quite as cut-and-dried as you might think.

As it turns out, it's relatively easy to trick the brain into hearing a sound that doesn't exist. Hearing is all about perception, and expectation plays a huge role. Your brain uses context to interpret the signals it receives from the sound waves that hit your ear. Research has found that when you expect to hear sound, the brain’s auditory cortex is activated in the same way as when you’re actually hearing sound.

The brain often fills in gaps where it thinks sound should exist, as the examples in the video show. This, AsapSCIENCE explains, is called “temporal induction.” That might mean hearing the words to Smash Mouth’s “All Star” when only a piano melody is playing, if you already know what the words should be. It might mean seeing a word written onscreen and hearing the full word in the audio track, even when part of the audio cuts out a syllable. Or it could mean hearing sound in a completely silent GIF, as many people do when they watch an image of a power line bouncing up and down.

Intrigued? Learn more in the video below, and then test your hearing on these other aural illusions.