Which way do you hear this audio illusion?

Listen to these notes. Does it sound like they’re going up or down? Your answer might actually depend on where you’re from. This is a specific interval called a tritone which takes an octave and divides it in half. So psychologist Diana Deutsch did an experiment. She played tritones in a bunch of octaves at once, making it hard to tell if they’re going up or down. And she took two groups of people and found that people from California tend to hear them going down and people from southern England tend to hear them going up. She thinks it’s all about the range of speech you heard when you were a kid, and Californians speak lower. So if you hear that first pattern which goes from D to G sharp as falling, you probably hear this second pattern which goes the exact same distance from A to D sharp, as rising or vice versa. What we hear might have to do more with us and our brain than what’s actually happening out there in the world. And you can hear more about this on Vox’s Unexplainable podcast.