The invention relates to an acoustic panel assembly. There is a need for a simple and inexpensive acoustic panel assembly. An acoustic panel assembly includes a rigid panel with an opening. The panel has an edge rib surrounding the opening, and a wall spaced apart from and surrounding the edge rib. The panel assembly also includes a frame member and a sound control sheet. The frame member has an outer border and a plurality of cross-pieces extending between different parts of the border. A compression rib projects forwardly from an inner edge of the border. The sound control sheet is mounted in and fills the opening. The sheet has an outer edge portion held between the rib of the rigid panel, the wall of the rigid panel, the border of the frame and the compression rib of the frame. The compression rib projects into a rear side of the sheet. The sheet forms a shoulder. The shoulder and the edge rib form a coach joint. The frame cross-pieces engaging a rear surface of the sheet. A plurality of retention points project from a rear surface of the edge rib. Each retention point projects into a fabric covered front surface of the sheet.