Through the sound field separation process, we decouple the active noise control system from the room environment. The decouple process translates the challenging problem of active noise control in a room into a simple free field noise field control problem. The proposed ANC system does not need the knowledge of the full secondary  path to design the secondary source output, thus there is no need for online secondary path estimation. By cancelling the outgoing field only, the ANC system’s influence on the  desired sound fields in the room is reduced.