Abstract: An acoustical panel assembly for a suspended ceiling comprising a rigid frame, sound absorbing material, sound transmission attenuation material and a face fabric. The frame is an assembly of extruded members secured together in a polygonal pattern such as a square or a rectangle. The fabric is secured to the frame by gripping elements integral with the frame. Marginal portions of the fabric are captured and hidden in receiving chambers formed by the frame members.

Abstract: A modified dovetail joint interconnects a plywood web to a chord. The chord carries two grooves extending inwardly from the surface of the chord intersected by the web. The two grooves merge into a single, wider groove adjacent the surface of the chord, are separated by a wedge-shaped spacer, and are inclined relative to each other. The plywood web carries two flexible tongues along its edge portion that are sized to engage respective ones of the grooves in the chord. The tongues are composed, at least in part, of two of the veneer layers of the plywood and are spaced from each other by a web groove formed in an intervening layer of veneer. The inner terminus of the web groove as well as the terminus of the glue laminate between the tongue forming layers of veneer and the adjacent intervening layer both lie below the surface of the chord when the web and the chord are assembled.