Drive noise is a bit of a pot-luck thing. I have a Mac Pro (4,1) which was basically silent new. After a year, one drive died, and I replaced it with the same model bought from Apple -- and it was a lot noisier. (Seek noise, fortunately, not so much spin noise.) Now, 6 years later, I replaced all the drives with new WD Blacks and the ones I got are close to dead silent -- yet many of the online WD Black reviews complain about how noisy they are! One of the two new WD Blacks has some audible bearing hiss, luckily not a problem when the box is closed up; the other is inaudible even when my ear is next to it.
I'm afraid that you most likely got a drive that's at the upper end of noise tolerance. Your best bet is to not notice it any more. 🙂 If you still have apple care, second best is to ensure that it fails (!) and get a replacement.