I`ve got the same problem with my WD80EFAX (WD Red):
Thanks. This could mean that all WD’s helium filled drives suffer from the same noise problem.
Well… My WD80EFAX with AIR inside. There’s no helium 
You are correct. The older models use to have helium, but the newer models like EFAX use air. So that means that we can conclude that helium is not a prerequisite.
So far 8 TB and 10 TB are known to have this problem. I’s likely that all newer models(8TB+) have the same problem, considering that WD doesn’t seem to think there is a problem to begin with.
So I would be surprised if the bigger models doesn’t have it as well.
After a Long time I wanted to contribute something:
I have made a timetable for the running times and stopped copying small files like Pictures on the disks….only big files for saving Images and so on…after several motnhs I cannot hear These noises anymore……Maybe the noise is from creating thumbnails, and after all files are indicated the noise stops???
Hmm, maybe? I don’t have any pictures on my drives though, only media files. And as far as I know, windows 10 doesn’t seem to create any thumbnails for them either. I have turned of all kinds of indexing also.
But my QTS operating System from QNAP does this……but I don´t know how Long it takes to do this…but my QNAP 453DX is quiet now…and Thumbnails could be made out of media files as well….but of Course the more files the longer it takes to do this…
No indexing is being done on my Synology NAS and I’ve had the 10 TB drives for about 1 1/2 years, and they haven’t quiet down yet 
So it’s still a mystery to me what causes the drives to make that sound. There must be some processes WD is running on the drives, as mentioned before it might be connected to maintenance, to keep the drives from losing performance. But who knows for sure, it’s a mystery.
You might be Right…I also think that the Sound is not a sign of a failure of the drives
But What I do know: they were my last HDDs, from now on I only will buy SSDs !!!
I’m looking forward to the day large SSD’s(10+ TB) are affordable, they still cost a fortune and not meant for home use
So for storage I think we have to live with HDD’s for the foreseeable future 
https://www.micron.com/products/solid-state-drives/product-lines/5210
here is a 8TB affordable SSD…unfortunately I couldn´t find any compatibility sign at the QNAP Homepage…they only test and/or Mention small SSDs…
It’s compatible with my Synology, but it cost 3 times as much as a WD Red. So I’m still hoping for a lower price and more capacity in the future
It would be super nice to have a NAS filled with big SSD’s. But the cost is too high, for me at least
Sorry for my bad english!
Well… It beeps too. But…
Both drives are installed in 2-bay DS218j. This new drive works as Disk1. And it starts at midnight (12:01 am | 00:01). Results:
-Disk1 beeps for about 15 minutes. Disk2 goes silent.
-Disk1 stops beeping, but Disk2 starts doing this.
-Disk2 stops beeping after ~10 minutes.
It beeps even hard activity (reading big chunks of data + rebuilding the RAID).
I have bouught 2 14 TB WD Red drives (taken out from WD Book duo) to replace my 10 TB drives. I had already 10 days “experience” with thoose disks. I didnt had beeping sound yet, keep fingers crossed ;).
Please let us know how it goes 
I can sadly confirm that 14TB drives have same issue 
Only plus that it is quiter and much shorter time of beeping sound, this is probably a reason why I didn’t heard it before.
Thanks for the update
Ok, 1 month passed and it still making beep sounds. And I just say “Ok, I can deal with it”.
One of my bro have got 2xWD80EFZX, and they’re silent. No beeps. Magic…
We think that these beeping sounds is something like “self-diag procedure”. Seagate 7200.11, as I remember, have got this too, but much louder.
(my eng skills is still trash, sry)
