I saw a video on YouTube that suggests that layers of towels are actually the best sound insulation. I'm thinking about putting folded towels in between the joists under the floorboards on the first floor, so that sound from the room above does not travel to the room below.
Do you think this would increase the fire risk to an unacceptable level?
EDIT - Some extra details: the towels will be placed on top of the plasterboard ceiling. The room is 12 feet by 12 feet. The room above is a bedroom. The room below is a bedroom.