Abstract: A dash mat assembly (10) for installation in a vehicle includes an acoustic barrier layer (12) attached to an absorber layer (14). The acoustic barrier layer (12) is formed of relatively stiff material while the absorber layer (14) is formed of relatively flexible material. The inner surface of the acoustic, barrier layer (12) is in direct contact with the outer surface of the absorber layer. Fasteners (16) are provided for attaching the layers together. Each fastener has an elongate pin (22) with opposite ends and a flexible holding flange (24, 26) integrally molded at each end of the pin (22). The flanges (24, 26) normally extend generally transverse to a central axis of the pin and the length of each flange is greater than a cross-sectional dimension of the pin. The fasteners (16) extend completely through the acoustic barrier layer (12) and can, extend either partially or completely through the absorber layer (14).