Hearing Is Believing: How Audio Illusions Trick Your Brain

Your ears don’t always tell the truth. Audio illusions are a reminder that what we think we hear isn’t always what’s actually being said.

Take the infamous Yanny vs. Laurel debate from 2018.

One audio clip, two completely different words. Some people swore they heard “Yanny,” others heard “Laurel.” The truth? Both are in the recording—your brain just latches onto one set of frequencies and filters out the rest. The higher frequencies push “Yanny” to the front, the lower ones favour “Laurel.” Which one you hear can change depending on your device, your expectations—and your age. As we get older, we lose the ability to hear higher frequencies, making “Laurel” more likely to stand out.

Then there’s the McGurk Effect, where what you see someone saying changes what you hear. Watch a video of a person mouthing “ba” while the audio says “fa,” and suddenly you’ll hear “fa.” Your brain merges the visual and audio cues and comes up with something that’s technically wrong, but feels right.

Or the Derby County chant illusion, where a TikTok clip of a crowd shouting something vague turns into whatever your brain is told to expect. Look at a list of possible phrases, and you’ll start hearing all of them—sometimes even ones that aren’t listed. It’s not that the crowd is saying all those things; it’s just your brain filling in the blanks.

The real trick? Your brain wants meaning. It grabs scraps of sound and slaps on whatever pattern it recognises fastest. And once it picks a version, it sticks—until someone else suggests another option and suddenly, you hear that instead.

Audio illusions show that our perception isn’t perfect.

It’s filtered, flawed, and easily fooled.

And honestly, that’s kind of fascinating.