Well I didn't know the doors, but the sentence felt so weird I had to look it up...
The literal meaning is " The doors sing", however this is an example of personification. So it means the doors are noisy.
I thought the sentence was referring to the rock band "The Doors." Wouldn't personification in this case be more recognisable to a Norwegian speaker if the sentence were something like, "Dørene er musikalsk?"
If its referring to the band, shouldnt their name be "the Doors" in norsk and english?
Èn if you want to accentuate that only one door is singing. En if you don't.
When I saw this I thought of Alice in Wonderland. Then I thought of a haunted hotel door.
Could it mean the wind is howling true the door when it's not closed properly?