Advice on the best soundproofing

Hi I am open to all suggestions for soundproofing I am constructing five gites from one barn and so need the dividing walls to be mega soundproofed I can’t build a solid concrete wall as I am on a wooden floor with a cellar below,any thoughts or anyone who has done something similar would be a great help.

I’m a sound studio designer about to relocate to 66000. I help out on stuff such as this myself - where are you based? I’ll be over again just after xmas. Feel free to email to discuss: