Soundproofing music facilities
Simple and cheap design features can go a long way toward soundproofing small rooms.
To avoid practice rooms sharing walls, locate non-music areas like offices, corridors, exits, and storage rooms/cupboards between practice rooms.
If practice rooms are adjoining, build a double wall between them (or erect a false wall in one of them), with blocks of polystyrene separating the framing to prevent transmission of sound. (You might be able to use lighter framing on one side to reduce cost.)
Create 'airlock' spaces outside practice rooms and recording studios.
Double glazing is essential, especially in windows facing into corridors.