You are right it is, which is why there is the requirement for an air gap and isolation of elements (floors to ceilings) if possible.
The White Book and Robust StandardDetails have a construction method for limited ceiling heights using, what they call, the “top hat section”, which is a channel section with isolating rubber to sit over the floor joists, it provides support for the insulation as well. Obviously this requires the lifting of the existing floor boards. Another easier way to isolate the floor is to overlay the existing floor boards with a new floating floor (MDF sheets on a rubber membrane).
Of course, this all becomes arbitrary, as your building control officers are not asking for tests, very lucky for you.
In our area of Kirklees they want the works, I even had to provide a noise report for the railway line running behind one of my properties. Maybe he had it in for me, as I argued the fire lobby requirements in an earlier flat conversion project, and subsequently had the building inspector overrule his plan requirements to suit my designed solution, and got it signed off as such.
Or maybe it was the planning officers, as I went over their head to the chief planning officer to get a permit issued, since the officer was raising unnecessary objections. Either way we’ve suffered since with their vindictiveness.