Disclosed is a method and apparatus for controlling the operation of a Cochlear implant prosthesis to optimise the effect of stimulation for a given patient. The device includes at least one mechanical stress sensor assigned to the register equipment. A filter element having fluted filter media is removable and replaceable from the air cleaner. When the portable computer system goes out of coverage, broadcast channels used by the wireless network are scanned by the DSP instead of the main processor to identify channels that have sufficient signal strength for the wireless connection. An optimum driving voltage for minimizing the ununiformity in color and luminance to be displayed is determined based on a signal detected by the light detection apparatus.