At first glance, it looks like a typo or a forgotten asset. But those who claim to have heard it describe something far stranger than a simple audio clip. The legend began in 2018 on a now-deleted subreddit dedicated to “corrupted nostalgia.” A user posted a single line: “Found an old G4 Power Mac at an estate sale. The only audio file on the drive was ‘superman.aiff.’ I’m not sure what I heard, but I can’t unhear it.”

“Think of it as sonic kryptonite,” they wrote in a 2021 blog post. “On a healthy, grounded machine, it plays as a clean, inspiring piece. But on a system with corrupted memory, failing capacitors, or a dying hard drive—that is, a machine that has lost its own ‘invulnerability’—the file self-corrupts. It becomes the sound of a hero falling apart.”

Just don’t be surprised if, when you hit play, you hear the sound of a man leaping—and not sure if he’ll land. Have you encountered a mysterious file like “superman.aiff”? Share your story in the comments. Or don’t. Some frequencies are better left unfound.