A sound treatment assembly includes an outlet member having a bore extending along a longitudinal axis, and a first flange portion is adapted to be coupled to portion of a valve body of a regulator valve. The first flange portion includes a contoured mating surface adapted to mate with a corresponding contoured portion of an exterior surface of the valve body. The outlet member also includes a second flange portion disposed at the second end. A diffuser assembly includes diffuser housing extending along the longitudinal axis, and a first flange portion is disposed at the first end of the diffuser housing and is adjacent to the second flange portion of the outlet member. One or more diffuser elements are disposed within an interior of the diffuser housing to reduce noise levels in the fluid exiting the outlet member.