Hello,
My Z3200 is on my print studio, separated from the the editing area by a glass panels and door, so the noise is not usually a problem to me. Anyway, when working perfectly the fan noise is never louder than the level of a noisy PC, but twice in 3.5 years I had issues with malfunctions related to the fans that made it get REALLY noisy. As my printer is under extended warranty they simply changed the whole power supply and never bothered to discover the real problem. My guess is that it was related to bearing problem on the fan or a loose screw somewhere near the fan or, even simpler as I had on my PC, a wire touching the fan. During the problems it was hard to bear the sound for more than a few minutes, even with the glass door closed and turning the printer off on the front panel did not solve it, I had to switch of the power supply.
Best regards.