What oto-more actually is
Step onto a Tokyo commuter train at 8 a.m. and the first thing that hits you is the quiet. Dozens of people packed shoulder to shoulder, and very little sound — few phone calls, no music, conversations usually dropped to a near-whisper. It’s a well-known Japanese public-space norm.
Into that silence, the faint metallic hiss escaping from someone’s earphones carries. It has a name: 音漏れ (oto-more), literally “sound leak.” You might not hear your own leak with the buds in your ears, but the person beside you often can — a tinny シャカシャカ (shaka-shaka) slips out even when the actual song is unintelligible. In a country this quiet on transit, oto-more is a real, named, low-grade annoyance that many riders notice.
The simple volume test
You don’t need a decibel meter. The trick is to leave the アナウンス (announcements) audible. If you genuinely can’t hear the conductor say the next station over your audio, your volume is probably high enough to be leaking. Turn it down until the ambient world — the rails, the chime, the doors — bleeds back into your ears. It’s a rough guide rather than a precise threshold.
And remember the counterintuitive one: 骨伝導 (kotsudendō / bone-conduction) and open-ear buds can leak more than sealed ones, because they never seal your ear in the first place. They’re fantastic for awareness while jogging, and a poor pick for a silent train.
Read the room, not just the train
The train is the strictest room, but it’s not the only one. A noisy street forgives a lot; a quiet study cafe forgives very little — loud audio there can annoy the tables around you. The single rule that covers all of it: read the baseline noise of the room and keep your leak below it. And audio aside, taking a voice call out loud at your seat is its own separate breach of train manners — railway operators ask passengers not to make calls in the car — step to the train’s end deck (デッキ) or the platform first.
Quick check
Three questions to lock in when your audio is staying yours and when it’s leaking into the room.