Please help with a noise diagnosis - "dragging" followed by water pouring

[Filink]

Hello everyone, I am Filink. I live in on 8th floor in an Toronto apartment complex built in the 70s.
Since I moved in here 5 months ago we have been hearing this weird dragging noise throughout the day. You can click on the links to hear it. It lead you to my Clyp page, not virus I promise.

Clip 1

Clip 2

We at first thought it is the upstairs neighbor's pressurized toilet, but when the building super flushed their toilet, we only hear an audible but obviously different noise (your familiar pressurized toilet swoosh). And now 5 months later we still have no clue. We tried having a building staff come to listen for it but it is extremely hard to catch. (and even if they did hear it they wouldn't know what it is.)

What we know:

1. The upstair neighbor only have one toilet, and it doesnt have different flush setting (excuse my terms)
2. The noise happens at least 8 times a day, sometimes it happens back to back 5 times within an hour. No one uses toilet that often. Added that to their also audible toilet we hear at least 20 noises throughout the day. Not fun
3. The dragging sometimes is not followed by water pouring.
4. The resident upstair is upset about we and the super frequently trying to flush their toilet and wont let us in unless we have a clear clue.

I am at loss on this issue. Would anyone here find this noise familiar and provide a guess? Any insight helps and please don't hesitate to ask for any clarification, I will try my best to answer. Thank you so much!

Filink
https://www.reddit.com/r/Plumbing/comments/qyo3u3/audio_linkedlooking_for_help_diagnosing_a/