I am at the initial stages of planning a house extension, about to engage the services of an architect, before costing, applying for planning permission and all the rest of it.
My girlfriend plays drums, I play various instruments, record and produce, so we intend to include a music/studio room on the ground floor of the two-storey extension.
I realise it is easier to install exterior noise mitigation measures from the ground up, as the room is being built, rather than trying to do it retrospectively. Hence I see this as the one and only opportunity I will have to build the music room I want, after (too many) years of compromise in existing spaces.
Ideally I want a room that I can sit in and near as little outside noise as possible. And, conversely, that the postie can walk past while my girlfriend is bashing away on her kit and be either unaware, or only just aware, of it. Or, even worse, hear me caterwauling

Budget will, of course, be a factor. So I can't afford to appoint a professional acoustic consultant to work hand-in-hand with the architect. However I do understand that the key to exterior noise mitigation is mass.
The plan is not to include large windows, because they would jar aesthetically with the rest of the property. I'm also not keen on the obsession with larch exteriors that domestic architects seem to be hung up on nowadays. Other than that, I'm open minded.
So, before I open negotiations with the architect, I would be grateful for any advice that anyone can offer on suitable materials and methods of construction to mitigate exterior noise, while at the same time hopefully not sending the council building regs peeps into meltdown.
Is it as simple as 'masonry walls as thick as you can make them', or would alternative methods like double-skinned walls with an air gap, or the gap filled with insulation, etc, be better?
I'm hoping that the ceiling insulation and carpet/furniture, air space and ceiling of the room above should deal with noise travelling upwards OK. (Plus, of course, I'll install internal acoustic treatment).
Also, are current standards of floor insulation (polystyrene blocks with concrete poured on top) enough to prevent the kick drum or my bass cabinet from shaking the postie's boots?
Any advice would be much appreciated.
Yours, excited but with a degree of trepidation...
Grater