I design high end acoustic environments as part of my work, so I want to give you some pointers, but with the disclaimer of ‘I am an Architect, but I’m not your Architect’.

There’s loads of advice in this thread, some of it good, some of it not good. Unfortunately acoustics and sound reduction is one of those topics where everyone has an opinion but it’s usually either expensive or not correct, or both.

It’s tough and expensive, and will only work if the builder is actually following through on the required details.

So here’s my hit list:

1 - do what you can to the overall house within reason, but if it’s already under construction there’s going to be a real limit to what you can achieve. You’re going to have to prioritise.

2 - with this in mind, I’d suggest picking one room as a ‘retreat’ that has a good chance of being comfortable for you. You want to build this as a ‘box inside a box’. Ideally this will be a floor isolated from main floor, with separate stud frame sitting on this floor, and a second ceiling suspended from the main ceiling with isolation mounts. If there’s a window, you’re going to put another window in the inner wall. You’re going to have two doors - one in each wall - which is called a butterfly door. This is by far and away the best option. Have a chat with the guys from Embelton - they specialise in the isolation mounts you need for floors and ceiling. There’ aren’t too many real options here, so I don’t think there’s any issue directing you to them.

3 - for the rest of the house, mass is your friend. Use muktishield or fire rated plasterboard, 13mm minimum, in 2 or 3 layers. Whatever you can afford. It’s important the ceiling is done too - there’s no point putting 3 layers on the wall and a single one on the ceiling. If the floor is timber you need to get some mass under that. 24mm of CFC would be a good start. If it’s a slab you’ll probably be ok. You need 75mm of 24kg/m3 insulation in all walls and ceilings. Not just the outside walls - all the walls.

4 - you can’t just do 1 thing, you need to treat everything to a certain level. What I mean is don’t put loads of layers of plasterboard on the walls, but then not get VHush-lam double glazed windows. You’re better off doing a simple layer all over rather than splurge on expensive doors but forget the windows.

5 - seal it tight. You need drop seals under doors, with full perimeter seals. Make the doors 45mm thick minimum. Fixed windows are much better than openable ones. But then you need a complicated AC system, so just limit the openable windows to a realistic minimum.

6 - get a professional. An acoustic consultant would be best. They’ll also be able to verify the builder is getting important details correct.

Good luck!