The present invention is directed to a tonneau cover incorporating a cable system which generates the proper amount of cross-car tension, and still provides for the tonneau cover to be rolled up and stowed when not in use. An array of acoustic sources is deployed in a marine environment. Each three adjacent pillars form an equilateral triangle, and each pillar comprises a semiconductor device. A protector plate is positioned within the pocket. In other embodiments, the target is moving in synchronization with the oscillatory motion of the adjacent players swing by a physical coupling or attachment.