Remove suspended ceilings in old building apartment

Dear florists,

For a few weeks now, I finally have the keys to my new old building apartment and we are busy renovating. According to the original 1910 building plans, the apartment should have a ceiling height of 3.36m. However, these ceilings are hung at different heights (aluminum slats with drywall), in the hallway at about 2.60m, in the rooms at about 3m. I would like the full height, so that last weekend, perhaps somewhat optimistically underestimating the work involved, we removed the suspended ceilings in the hallway and cut "peep holes" into the ceilings in the rooms. Result: at about 3.10m height there is still an old, possibly original suspended ceiling (plastered wooden frame with straw) and above that a wooden ceiling (beams, above them boards in good condition).

Now my question: apart from the work and the mess this entails, what should be considered when deciding whether to remove these old suspended ceilings? In particular: could it happen that we suddenly end up with no or significantly reduced sound and/or thermal insulation? It should be noted that the apartment is on the 4th floor, above is a newly converted attic apartment, probably with "modern" floors (probably screed, I would have to check).

Thanks & best regards,
Simon

at about 3.10m height there is still an old, possibly original intermediate ceiling (plastered wooden frame with straw)

Are you sure that this is not rather a Rabitz ceiling?

Could it happen that we then suddenly stand there without or with significantly reduced sound and/or thermal insulation?

And with reduced fire protection.