Chapter 1 — What did you just hear?

A puzzle to begin with

Hearing feels like one of the most transparent things you do. Air vibrates, your ears pick it up, you hear it. Nothing in between. The world is, audibly, what it is, and your ears tell you what is there. This is the everyday phenomenology of hearing, and I want to argue, slowly, over the next thirty thousand words, that it is wrong in a way that is more interesting than any other fact about being alive.

Let me start with a puzzle.

The four short sections below open the essay. We meet the bistable galloping triplet, listen to it, watch our percept flip, name what just happened, set out the journey ahead, and preview three more illusions whose explanations live later in the essay.