A three-dimensional rear projection screen that has substantially improved contrast by using a tinted layer disposed between the source of the projected light and the light diffusion layer. The method also includes sensing movement of the target marker, and modifying operation of the beam source based on the sensed movement. The hole can be used to fasten a surface snap member, which snaps together with the cover snap member. The audio signal may be filtered utilizing a pre-emphasis filter, such as an infinite impulse response filter and may be divided into frequency bands utilizing one or more finite impulse response filters andor delay modules. The doorplates are opened for allowing downward movement of the switching button to switch on power supply when the neutral and hot blades of an electric plug are respectively inserted into the neutral and hot slots.