What many people might not realize about sound in ultrarunning can probably be summed up in two key ideas.

The first is a little easier to grasp: in some of the top races, music and headphones are actually banned. While part of this is about safety, being aware of your surroundings, there’s another reason that cuts deeper. Music, for many of us, becomes a kind of drug. It helps us access specific emotions to get through hard moments. We’ve all felt this, whether it’s the song that lifts you after a promotion, or the one that gets you through heartbreak. It’s powerful, not because it’s a substance, but because of how deeply it affects the mind.

The second idea is more nuanced and rooted in the psychology of long-distance trail running. When you’re out there for hours, even days, without sleep, your perception begins to shift. In sound theory, there’s a concept called the “acousmatic”, sound heard without seeing its source. On the trail, this can be anything: footsteps behind you, a rock tumbling nearby, or even the rattle of a loose can in someone’s pack. These sounds usually have logical explanations, like another runner catching up. But as night falls, fatigue sets in, and your senses narrow to just what your headlamp reveals, those sounds can take on new meaning.

Your mind starts to fill in the blanks. A rustle in the bushes becomes an animal. A falling rock might feel like a threat. You begin to hallucinate, not just visually but sonically, your brain invents stories to explain what it hears. That’s how powerful sound becomes out there. When vision is limited, sound takes over. And in those moments, it can shape your entire psychological experience of the race.