if the door in the house has a draft or air current the door will slam harder because the doors moves more freely

if the house is tightly sealed no place for the air to be drawl in from shutting a door is softer the air is restricting so it makes the movement slower so less force when it closes less sound

the best way to see this is a place that is sealed well try to open the door fast u feel the pull back ....now open a window and do the same thing u see how easy/ fast it was