An acoustical panel assembly (10) includes a panel (12) having a core (13) made of synthetic material and an acoustical device (26) mounted to an exterior surface (14, 16) of the panel (12). The panel (12) may include an integrally formed attachment member (24) for mounting the acoustic device (26), such as a loudspeaker, an exciter, a piezoelectric transducer, or the like, directly to the panel (12) without the need of a separate mounting member. Alternatively, the acoustic device (26) may be mounted directly to the panel (12) without the use of the attachment member (24). The panel (12) can be formed by a reaction injection molding (RIM) process, a reinforced reaction injection molding (RRIM) process, or a structural reaction injection molding (SRIM) process.