New bathroom soundproofing

fifthofwhisky

Plan to remodel a bathroom in a 1960's semi. The joining wall looks like concrete block and I'm not sure if it's single block or double. In either case noise from next door travels through (from their bathroom and other rooms). Also want to try and reduce noise traveling across internal partitions to the rooms adjacent the bathroom. It's a tongue and groove wooden floor fitted across joists.

I could probably lose a few cm on the joining wall to add some kind of soundproofing. However, that wall would need to be solid and stable enough to be tiled and waterproof for a walk in shower.

Any suggestions for noise reduction measures please?