[Kye]

Bass can wiggle through walls in ways that surprise even the person generating it. Worse, the wall filters out much of the other frequencies that might make it bearable. I think most people with their music rattling through their car doors don't even realize it. Think about it: the only way they would know is if they left the music on, got out, and shut the door. Not a common occurrence.

Plenty of music people think to treat their rooms with the usual foam on the walls, but not everyone thinks (or cares) to treat it with bass traps.