The caulking mentioned is fine to seals the gape but you may need somethingto back it other thatn backer rod. in that case you may need a small amount of Rockwool insulation to pack into the void befo ... read more
You might consider trying to add a new layer of ceiling drywall using GreenGlue sound proofing adheasive. This gets installed without removing anything too, it should be noted . This will be the most ... read more