[TheOtherHobbes]

Sound treatment uses acoustic panels to make a room with a flat frequency response and minimal reverb. They damp the room's natural resonant peaks and reflections.

Sound isolation keeps sound from getting into and out of the room. It's a separate problem, and you can only solve it with mass and physical separation - e.g. building a room inside a room with massive walls and rubber isolation for the floor.

If you do it properly you have to pay a consultant to design a solution for you, because it's so easy to get it wrong.