Quiz time! Guess the noise!

Attached to this post is an audio file. Have a listen and guess the origin.

I recorded this in my rented co-working office space. It's super loud and annoying and has been happening for months.

Engineers have now discovered the source!

Clues:
* I am on the 2nd of 4 floors
* It's intermittent and can happen a few times a day, or 5 times in 5 minutes.
* There is a bathroom nearby
* There are other offices nearby
* It does not come from my office (or me)

Guess!

Bonus clues:

* It can last as long as 15 seconds or as short as 5
* It's been happening since at least August last year, but I have noticed more as I am here more often

Further bonus clue.

* The *office* from where the noise comes is a "call-centre".

Final clue (will reveal later today)..

* The device now has a "Do not use" sign on it. :D

@popey I didn’t know faucets ran DNS these days… blimey! So many tech advances
@popey
A shredder?
@robert A popular but incorrect suggestion.
@popey It's gotta be DNS, it is ALWAYS DNS

@popey automatic fan in some rarely used toilet gone bust?

Coffee grinder?

@popey did I guess right :-) ?
@zygoon nobody has has yet guessed the specific item.

@popey ahhhh

What is it!?

The sound reminds me of a weird pipe rattle but my mind also said “cursed DVD drive in some old office printer” and “someone rebooting a SUN workstation in the closet”.

@popey mains (water) water cooler?
@bigcalm @popey yea with you on that one, its got that kinda rubber diaphragm noise, almost pump like
@popey call centre staff screaming into the void?
@popey Oh, then it'll be the screams of the damned.
@popey It'll be their tree chipper, then. Gotta dispose of the non-closers somehow.
@popey that's an oddly specific spelling. Is there a relation to the origin of the noise ?
@frenchguych Which word did I spell weirdly?
@popey it the double quotes and the dash between the words that tricked my weird mine into thinking it was a clue !
@frenchguych Hah! My clues are not that deep :)
@popey then I guess the word *office* between two stars ain't a clue either ?
@popey is it like their version of a sales bell/account deal made kinda thing ?