Strange tapping noise
This is going to sound bizarre, but here goes: I live in an apartment building with (albeit) thin walls. I have very sensitive ears for some things. About a week ago, I started hearing a strange, soft tapping noise. It seems to come from the apartment underneath me and it is a series of three taps (always three), spaced out over a few seconds. I can't imagine what it could be and I'm desperately grasping for ideas. It's not a dripping sound, as if a pipe was leaking, and the fact that it is ALWAYS a series of three taps really has me befuddled. But it is akin to the Chinese water torture, if you know what I mean. I thought it was only when they were home and therefore maybe it was some machine they were running, but I heard it this morning and I believe everyone had already left for work.
I would like to have some possibilities of what it could be before I either knock on their door and ask or talk to the building manager.
Does anyone have any ideas??