I don't know where it really was originally, but if it was ever really in the stovepipe like it sounded like, it somehow managed to get out by itself tonight. Last night I gave up on the horrible thing and stuck earplugs in my ears and somehow managed to fall asleep, despite the fact that the horrible thing was so LOUD that even with earplugs in it was louder than any normal human speaking voice. I don't know whether to attribute my ability to fall asleep primarily to my state of sleep-deprivation or primarily to my long-standing talent for falling asleep immediately under any and all circumstances whenever I try to do so, but it definitely surprised me that I succeeded at falling asleep last night (and staying asleep too! and waking up to the sound of my alarm clock despite it being slightly muffled by earplugs!).
Anyway, the thing wasn't making any noise anymore when I came home from work today, but I knew it was probably still around. And sure enough, 6 hours after I got home, suddenly there was a loud metallic CLANG! from my kitchen, and then another, and another, like a cat or a small child was bouncing a metal ball around on the floor. It sounded much too large to be an insect, but it was highly unlikely that a cat or a small child would have gotten into my kitchen, whereas I had good reason to believe that an insect was in there. So I put my glasses on, and went into the kitchen with much trepidation . . . and sure enough, there was a humongous shiny black cricket hopping around on my floor. It must have clanged into the the metal dishwasher repeatedly or something. But it's dead now! Very dead. And definitely a cricket.
Last night while I was wondering what it was, I consulted this website, which informed me that "Crickets' songs are musical to the human ear because their carrier frequencies are relatively pure and low." The idea of anyone describing the godawful ear-piercingly high-pitched shrieking noise that this thing was making last night as "musical to the human ear" or "relatively pure and low" was so unthinkable that I concluded, on this basis, that it must definitely not be a cricket. But from the sight of it, it is every inch unmistakably a cricket! The authors of that website have no idea how misinformed they are.