An apparatus for use in kiosks or other computerized devices for filtering out selected key codes transmitted between an input device, such as a keyboard, and a host computer. The elastic region width varies from a terminal end of the elastic tab to a proximal end of the elastic tab such that a width adjacent the terminal end is 20 to 80 percent narrower than a width adjacent the proximal end. The fiber-optic taper forms a loop, the center taper segment remaining substantially straight and opposite the crossing point of the loop. The modified decomposition components may be reconstructed to generate an artifact-compensated signal which may be provided to a monitor or other device which is otherwise not configured to compensate for signal artifacts.