I don't think it's possible to build apartments or other connected houses in a way that isolates each unit from another, not without losing the efficiency / cost benefits of connected housing. Case in point, I live in a row of houses, but they just use long slabs of concrete for the flooring, creating a hard connection between the houses.

Mind you, it's fine (for me) most of the time, it's only really an issue if someone starts drilling / does anything in direct contact with the floors / walls.