Abstract: A center plug for attenuating noise in a gas turbine engine includes an inner skin, the inner skin having a substantially cylindrical shape and extending along an axial centerline; a forward bulkhead disposed proximate a forward end of the inner skin, the forward bulkhead connected to and extending radially outward from the inner skin; an aft bulkhead disposed proximate an aft end of the inner skin, the aft bulkhead connected to and extending radially outward from the inner skin; and an intermediate bulkhead, the intermediate bulkhead positioned intermediate the forward bulkhead and the aft bulkhead, the intermediate bulkhead spaced a distance from the inner skin and extending radially outward from the inner skin, the distance defining a radially inner portion of the intermediate bulkhead and an annular opening.