Soundproofing is vital when constructing music studios. This the the thing not be neglected at all when thinking about creating a studio for making high volume music.
Soundproofing is not something really hard to understand in itself, but it's difficult because you need to be very cautions and think about all the little details that could lead in sound leaks.
What's very difficult in soundproofing is to isolate from low frequencies at high volume. Things like drum or sub woofers that generate frequencies from 15Hz to 500Hz at sometimes more than 100dB are a real pain, mostly because they're propagating.
Sound is like water. If the room you want soundproofed isn't totally hermetic, the sound will leak. But low frequencies are more like vibrations, so it propagate through material until they're connected to each other.
This is why we often talk about "box in the box" when it comes to soundproofing.
The "box in the box" technique is litteraly recreating a room in a room : new floor, new ceil, new walls, new door. The goal is that the inner room is connected as little as possible to the outer room, so low frequencies can't propagates.
For all other kind of frequencies and airborne sounds, it's mostly solved by using very bold walls, constructed out of porous materials.
References :
- [30 types of soundproofing materials explained](https://www.acoustiblok.co.uk/soundproofing-materials/#Absorption)