A monopole low frequency test woofer (10) has a rigid mounting plate (12) with an acoustical opening (14), a monopole driver (16) with a high mass cone and low resonance mounted on the mounting plate with the basket (13) of the driver fitting about the opening, and a rear tub (20) attached to the mounting plate forming a sealed enclosure about the driver. An inductor (18) is also in connected in series with the monopole driver inside the enclosure. The sealed enclosure has an electrical connector (26) for making connection to an external circuit. The difference in outputs between the test woofer and standard optimized speaker represents the loss in baffling due to the vehicle environment being less than ideal.