Our household has taken on a new resident: A genius cricket.
While crickets are very good at naturally taking up positions that are hard for humans to reach, this cricket has located quite possibly the best possible position in the entire household: Deep inside our furnace, as near as I can tell. I haven't made visual contact yet so I'm not sure, but he's definitely in the furnace room.
Crickets are known for their chirp (which only male crickets can do; male wings have ridges or "teeth" that act like a "comb and file" instrument).... Crickets chirp at different rates depending both on their species and the temperature of their environment. Most species chirp at higher rates the higher the temperature is (approx. 60 chirps a minute at 13ºC in one common species; each species has its own rate). - Crickets
Definitely a male. And since he's in the furnace, it's pretty warm. When he chirps, he's really going at it.
The reason I say he's a genius is that that is the one spot in the entire house I absolutely can not get him. The only option is to spray a poison at him, but I can't spray anything into a furnace with a pilot light without risking a lot more than some annoying chirping. And he seems to know better than to wander out of his safety zone. Even our cricket-seeking cats can't get at him.