Both flat-panel and conventional speakers use electric motors to create the vibrations that reproduce sound. But that's where the similarity ends.
In a conventional speaker, a motor moves back and forth at the apex of cone-shaped speaker material, creating sound that is beamed outward from the cone.
In a flat-panel speaker, one or more small motors known as exciters vibrate to generate bending waves across the surface of a panel.
The panel can have virtually any shape and can be made from a variety of materials - including fiberglass, carbon fiber or polycarbonates - as long as the exact position of each exciter is calculated during the design process.
The movement of the panel reproduces the input sound and distributes it in every direction. There is no "beamed" effect as with conventional speakers.
With an NXT system called DirectDrive, an interior trim panel effectively becomes an individual loudspeaker, allowing designers to integrate audio into any interior part, including the headliner, sun visors, door trim or headrests.
In the Buick Bengal concept, the entire instrument panel was an audio speaker. The system can save four pounds per vehicle.
British automaker TVR is using another NXT technology. It combines conventional piston-cone technology and flat panels to reproduce all audio frequencies. TVR mixes 2½-inch-diameter flat panels with conventional woofers.