Headphones are personal bubbles; speakers burst them. Keep volumes low enough that neighbors hear only faint whispers between stops. Open-back designs leak; closed-back helps. Remove one ear when announcements begin, and stash jingling accessories. Respect riders decompressing after night shifts or studying their last-minute notes. Shared air means sharing silence, too, so your playlist does not become an unsolicited station soundtrack.
If a call is urgent, keep it brief, measured, and close to your lips with a hand shielding sound. Skip speakerphone entirely. Many cities discourage calls in designated quiet cars, and some commuters treat any carriage as a library before 9 a.m. Text when possible, apologize if noise spills over, and end the moment reception cuts, rather than shouting into tunnels and echoes.