I dont experience this sound. At first I experienced a "click" when I start and stop the movie. After some time the "click" sound dissapeared , I suppose the tactile contact gets used and finaly dosnt make this noice ?
I asked Casio and got the following answer:
"The microphone of the camera is very sensitive and therefore it might pick up
some extra sounds.
We suggest to use the infinity zooming (symbol is like an 8, horizontal) or the
Pan Focus (page 78 from the instruction manual in the CD-Rom. This ones
deactivate the auto focus and you will reduce (or will not have) the noises in
Anyway, as a electronical enigneer I know that a LCD dosnt make any noice at all, so the sound must come from a different source.
The only electronical component that can make the noice you describe is a coil windings vibrating, such a coil is usualy placed in the power supply. Then its a design error, or they use a low quality coil, but I find this very unlikly. More likley its a motor or other mechanical source.
Does your camera say Made in Japan ?
It could also be a mic/speaker issue, you know the problem from people speaking into a mic and the mic picks up the sound form the speaker. In this case its a volume setting, and can be updated by firmware.