An enclosed resonator includes a generally planar plate having a top side and a bottom side wherein a pocket is recessed into the bottom side to produce a bottom surface and a periphery around the rectangular pocket including a first pair of parallel sides and a second pair of parallel sides, a plurality of generally parallel channels formed into the top side each channel extending generally in a direction of the second pair of parallel sides, a first plurality of holes extending along a first side of the first pair of parallel sides each hole extending from the bottom side to one of the plurality of generally parallel channels, a second plurality of holes extending along a second side of the first pair of parallel sides each hole extending from the bottom side to one of the plurality of generally parallel channels.