Think about what? If the tv is too loud you knock on the door and ask them to turn it down. If they don't answer you contact the landlord or the cops.
We have no way of knowing how loud the sounds the guy heard were. There is nothing in the story to suggest any other neighbors heard anything out of the ordinary or thought something was wrong.
Just Conan, the guy who doesn't have a phone and lives with his mom, who felt it appropriate to kick in a door brandishing a sword, rather than make any effort to call the police or raise the hue and cry amongst the citizenry.
