Conventional speakers use motors, called drivers, to convert electrical signals into motion that vibrates a cone of material suspended in a cabinet or other enclosure. The vibrating cone generates waves of varying pressure in the atmosphere that the human ear interprets as sound.
In a so-called flat-panel speaker, the motor works roughly the same way, but it vibrates a simple panel — plastic, metal, composite or other material — and eliminates the complex structure of conventional speakers. The entire panel vibrates to create sound waves. It can be small or large and as thin as 0.01 inches. Each panel can be a flat, curved or complex shape.
British supplier NXT has developed two distinct technologies for automotive use. In direct-drive form an interior trim panel — headliner, door panel, sun visor, even the entire instrument panel — effectively becomes the speaker. A second technology combines panels with conventional woofers to overcome flat-panels' weakness at reproducing low bass sounds below 200 megahertz.