A combined baffle and reinforcing assembly is provided for use within the cavity of a structural member to dampen acoustic transmissions through the cavity and provide reinforcement in a direction transverse to the longitudinal axis of the structural member. The assembly includes a synthetic carrier which includes an interior area, marginal rim, and an attachment member preferably in the form of a clip for insertion to the corresponding hole in the wall of the structural member, and a circumscribing and continuous band of reinforcing material extending around the periphery of the carrier. The assembly may be economically manufactured by co-injection molding or insert molding of the thermally expansible material around the carrier. The marginal rim of the carrier may include base wall and a support flange for receiving the thermally expansible material thereon. After activation of the expansible material, it expands outwardly and bonds the carrier to the surrounding wall of the structural member, leaving an interior area of the carrier uncovered by the foamed expanded material.