The Atlantic’s “How Headphones Changed the World” discusses how we use headphones to control our individual experience in the public environment, especially in cities. With urban living comes a loss of physical space and agency—and that’s nowhere more apparent than on public transit. Stuck in a stalled BART train 40 meters beneath the floor of the bay between a crying baby and a man surreptitiously eating his boogers? Yeah, headphones are nice.

Personal music creates a shield both for listeners and for those walking around us. Headphones make their own rules of etiquette. We assume that people wearing them are busy or oblivious, so now people wear them to appear busy or oblivious—even without music.

I’ll admit to doing this. Insert earbuds and instantly I’m above suspicion of eavesdropping. 

These errors of assumption go both ways, though: If observers believe that listeners aren’t observing, listeners believe that observers aren’t listening. Which of course is untrue, especially if you were the dozing, pouty-faced girl blaring tinny Rhianna out of your ears this morning. Yeah, thanks for that.

Excessive headphone volume is a high crime of the commute hour comparable to standing on the left side of the escalator or failing to yield to the pregnant lady. What’s unique about this transgression—what tempers my usual righteousness—is that I have no way of knowing if I myself am an offender. Paranoia that my neighbor may be ridiculing or resentful of my Taylor Swift playlist plagues me. And how would I even know unless someone told me?

Despite the widespread abuse of headphones, I’ve seen such an interaction only once. A man tapped a middle-aged woman on the shoulder. I didn’t catch what he said to her, but he had a pleasant, open face and didn’t appear unkind.

“Oh my god,” she said, “I’m so embarrassed.” She frantically thumbed the volume button on the side of her pink iPod. “Now everyone knows I listen to the Carpenters!”