Drives are not failing right now. The 80's were not as quiet as the Raptors, they were multiplatter drives.

What you can do to dampen some of the noise is check how they are screwed in. There are small plumbing o-rings that can be put between the screw head and the case part that the drives ride inside of way back when all drives came with rubber shock absorbers to isolate the drive from the case, but since silicone rubber formed parts were expensive(and regular rubber would rot and drop stuff that caused overheat since rubber also insulates) they were only used when needed.

What you hear is probably two things in combo-- First, the drives gen heat, decent amounts. A fan with a speed thermistor, or a box with thermal speed control on mobo for fans and\or fans that exhaust and have a thermal speed control will spool up some when heat rises. They may not spool up to full speed, but enough to raise the ambient noise when the HDs are on and generating heat.

The other is the most common:

You need to make sure the drives are tightly screwed in palce, in the case, too. Reason, a loose screw is being vibrated by the drive and that vibrates against the head of the screw against the case. The drives need to be tightly mounted bacuse good cases absorb the sound with it spread through the case metal which is thick enough to not broadcast it.

Maxtors did two things endemically that made Maxtor silence them (So did Seagates)-- they viobrated more than WDs and also they were more shock sensitive than the drives you have. Thethings that were added dampened noise and stopped the vibration and protected the drive if the case was jostled or dropped.

WD builds industrial grade drives that last and last-- this requires metal (which transmits noise lots more) where others use nylon, but the drives innards do not wobble as much with nylon and the nylon is quieter (it also wears out faster than metal, the drives go unstable for fine head posistioning versus the drive platter,and they wear out sooner).

The other thing is that WD uses harder plastics inside where they need to than the slightly softer plastics used to dampen noise. These lastlonger and are better able to retain shape more perfectly than others with softer plastics. I have had surged trashed drives apart to look forensicly where mfrs can tell from what happened means no warranty. What I say is consistent through many years, a couple of decades.

The problem with using the best noise insulators is you either trap heat and drive gets heat damaged, or you have to use harder more noise transmittive material to retain shape with heat changes.

Now, industrial grade HDs use metal platters coated with magnetic media. These transmit some noise. Your Western Digitals have these because they are high speed and fast accelleration drives. The motors are not bad, nor the platters, nor the bearings. The whole design to make them very heat safe transmits a bit more noise and the harder materials are part of that design. Steel is usually used, more than Aluminum, because the softer alloys also change size more dynamicly as heat levelschange.

If they were broken much at all the noise would be such that you would hear them over fans, a radio, or a TV.

Summary, WD designs more for stability and security and heat dissipation (drive safety). Others that sell quiet at same price are trapping heat or using materials that will not last as long to be quieter, and sacrificing durability and initial data feed speed from rest. Best noise dampener is heavy metal case with short tight screws, and 1\16th to 3\32th of an inch ID plumbing o-rings (which are safe and are silicone rubber usually these days) put between case and screw head. This way the case absorbs vibration (one mil steel does this well, Antec cases do this very well), and the screw will not vibrate loose.

Every once in a while you will find that it is a good idea to tighten screws and check cases for looseness and lack of regidity. This gives you electrical safety inside the case also, and keeps screws from shorting something when they fall off. When you clean out case with an air can also do screw maintainance with anti-static strap on and connected if needed and power off.