Which way is up?

You'll hear two notes half an octave apart. Say whether the second one goes up or down. There's no right answer, only your answer, and it's surprisingly stable.

12 pairs · about two minutes · headphones help

What's going on

Each note is a Shepard tone: the same pitch stacked across many octaves under a fixed loudness curve. It has a clear note name but no clear height. A pair a tritone apart sits exactly opposite on the circle, so up and down are equally short. Your brain has to choose, and it chooses consistently.

Diana Deutsch found that the choice depends on where you grew up. Listeners from southern England and from California tended to have their "high" region on roughly opposite sides of the circle. Her account is that it follows the pitch range of the speech you heard as a child.

The dial shows each pitch class you started from. Red means you heard that pair fall, so the first note sounded higher. The needle points at the region you hear as highest. A long needle means you were consistent; a short one means it's a toss-up for you, which is also a real result.

Every tone uses the same spectral envelope, so loudness and brightness give no clue. Overall level rises and falls gently across the session so it doesn't feel like a hearing test, but both notes in a pair are always equally loud.