I experienced this sort of thing from the other end a few years back. I'd just moved into an apartment, and one of my neighbors starts filing almost-daily noise complaints against me.
Among his complaints were blaring TV and music at all hours of the night and day, people stomping around constantly (his apartment was directly below mine), screaming children, weird rumbling noises and odd popping noises. The popping noises thing was the only one I figure might have been me (I play first-person shooters), so I started turning the volume down when playing with my XBox. The rest I either couldn't hear at all, or were obviously coming from somewhere else (for example, the apartment management was refinishing the roof around the time I moved in). Aside from needing a TV for my XBox, I almost never turned it on, and the only music player I owned at the time had no speakers, only earbuds.
Then I started hearing an inexplicable noise. I'd be laying in bed, falling asleep. The entire apartment as dead quiet as it ever gets, just the refrigerator hum keeping it from being perfect silence. Then BAM BAM BAM! This odd and very loud banging noise would resound through the building. It never persisted long enough to pinpoint it. I was thinking air hammer in the pipes, and it took me several days of it to figure out. It only happened late in the evening. Eventually I decided to sit up and wait for it, to try to pinpoint it. As it happened, it was my downstairs neighbor banging on his ceiling with a broom handle. Mind you, at the time it happened, the banging was the ONLY loud noise; When the old coot wasn't banging away, the loudest noise was a quiet refrigerator hum from the kitchen. Having figured it out, I waited for him to start pounding again, and pounded back. The next day, he was waiting at the manager's office when it opened, to deliver a "him or me" ultimatum.
It never occurred to the man to ASK if I was the source of the noise. Or to wonder if the construction crews might have had something to do with it. I managed to get it settled through the manager as a go-between, and didn't even meet the complainer until a few months later. Turns out the guy is almost completely deaf (!!!), wears a huge hearing aid in each ear, and even with them on, has great difficulty hearing a normal conversational tone from three feet away, he gets by with lip reading most of the time.
To this day, I truly believe he was somehow getting radio reception on the hearing aid. It's the only way to explain the loud TV and music issue he had.