The walls are thin. Plan for it rather than hope.

Honestly what you can expect: normal speaking volume from the next room is audible as sound and often as words. Alarms, doors, footsteps in the corridor, someone's video at 1am — all of it comes through. Some newer buildings are noticeably better; older ones are partitions with wallpaper.

So yes, they can hear you, and that is the part that matters for your speaking homework.

What students actually do about the practice problem:

1. Do speaking work outside the room. A study cafe (스터디카페) is 2,000 to 4,000 won an hour, everyone there has headphones on, and nobody cares if you mutter. This is the standard solution and it works better than whispering at your desk.
2. Practise in the shower cubicle with the fan on. Sounds absurd, is genuinely common.
3. Record yourself on the walk to class. Nobody on a Seoul street will notice one person talking to their phone.
4. Keep it to daytime. Speaking at normal volume at 2pm is fine; at 11pm it is not.

For the light-sleeper half:

- Earplugs. Everyone who lives in a goshiwon owns them. Foam ones, a big box, they cost nothing.
- A white noise app or a small fan. This does more than earplugs for most people because it masks rather than blocks.
- Ask which floor and which side when you view. Rooms next to the kitchen, the entrance or the laundry get the most traffic noise. A room at the end of a corridor is quieter.
- Visit at 8am if you can. That tells you more about the building than any listing.

One thing worth knowing about the culture: goshiwon have stricter quiet expectations than most housing precisely because the walls are thin, and originally because everyone in them was studying for exams. Complaints do happen and they go to the operator, who will pass them on. That cuts both ways — it means your neighbours are also being asked to keep it down.