Conspiracy or Insanity

So, there's either a conspiracy against me or I'm going completely insane. Since I've gotten back to Waterloo after my vacation, there's been an alarm going off in someone's apartment near mine every night from midnight until 2am. It's a pretty faint noise, but at that time when all is quiet and I'm trying to fall asleep, it's quite noticeable. At first, I thought it was coming from the apartment above me, since ususally, sound travels down in apartments. So, I brought it to the attention of my super, and he said that the guy above me works midnights, so it's a good possibility that he's not home when it goes off. Turns out, however, that it's not coming from his apartment....

So, the night before last I do some more investigating, trying to pinpoint the source of the sound. It's very hard to tell exactly which direction it's coming from in my apartment, because it's coming through the walls and therefore seems to be coming from everywhere. So, I head out into the hallways and discover I can't hear it outside my apartment. Same thing about the floor above me. However, I can hear it when I stand outside the apartment below me. So, this leads me to think that it's the apartment below me that the offending alarm resides. I notify the super with the new information....

This morning (after the alarm still persisting last night), I get a call from my super saying the people below me say it's not coming from their apartment.

This noise has to be coming from somewhere, and I guarantee it's not coming from my apartment (and by guarantee, I mean pretty sure). And why am I the only one who hears it? Wouldn't someone else hear it too? Of course, most people are older in my building and therefore are asleep at midnight. But wouldn't the people living in the apartment where it's coming from hear it at some point? So, either there are some who are conspiring against me to keep the alarm on or... I've gone completely insane. Probably from lack of sleep from hearing this alarm.