The invention provides, in one aspect, a loudspeaker that has electrodynamically-driven piston mounted in one external wall and that has movable panels in one or more other external walls. Those panels are air-coupled to the piston, e.g., via air within the enclosure, such that vibrational motion of the piston causes the vibration of the panels, thereby, improving the overall air coupling of the piston to the external environment, e.g., the listening room. Further aspects of the invention provide an improved driver for use, e.g., in the aforementioned loudspeaker. The driver comprises a three-part piston having first and second diaphragms coupled back-to-back with one another and having a voice coil face-mounted (or front-mounted) within the second diaphragm.