XPS 16 9640, XPS 15 9530, WD22TB4 high pitched noise

I have this exact same issue. 

I have tried two separate WD22TB4 docks with my XPS 16 9640. Both cause the laptop to make a high pitch sound from the USB-C port. Doesn't matter what port I plug into, either of the two on the left or the one on the right. 

I have tried disconnecting everything from the dock except for power, and the noise is still there.

Laptop with charger makes no sound.

My old XPS 15 9500 does NOT make the sound when plugged into dock.

I did try a co-workers XPS 15 9530, and it DID make the same high pitch noise.

It is driving me insane.

Using XPS 16 9640 and WD22TB4. If I plug in a separate ACDC adapter into the laptop, then plug in the docking station I get no high pitch noise. The moment I unplug the separate ACDC adapter from the laptop; the high pitch noise is back. If I then plug back in the separate ACDC adapter the high pitch noise is still there. I have to unplug then plug back in the docking station to stop the high pitch noise.

I've been facing the same problem and a replacement has not resolved the issue. My post here : XPS16 9640 + WD22TB4 Dock High Pitched Sound

This Dell KB article was updated today =

Buzzing Noise from Dell Docks When Connected to Dell Laptops