Yeah, the case fans have a really high pitched whine. Like too many rpms. Think of the motorcycle thing in the last few Batman movies.
The drobos were fairly quiet for the most part, but when you exit the computer out of sleep you would hear the disks ramp up and/or click on.
For the La Cie, if you have a compartment out of the way it would probably conceal most of the noise. Like a closet or something.