The acoustical characteristics of both Raptors were similar. You will notice a slight whine during the spin-up phase on each drive along with the same whine when the drive powers down. The reads are clearly audible, but do not have the same metallic noise that we noticed on the Maxtor drives. During normal operations, both drives could be heard, but the sounds emitting from the drive was almost dull compared to the Maxtor drives. The WD1500 was slightly louder during constant read access compared to the WD740GD. While not obtrusive in our opinion, the sound levels would be clearly evident in a silent system.