A similar thing actually happened to me. I live in my parents' house, and then suddenly the smoke detector sounds off in a high-shrill, beeping, annoying, yet continuously beeping noise. It basically indicates the battery's about to die. I have slept through that many times, what seemed like weeks, so I guess the battery's lasting for quite long. Now it goes on and off intermittently. I simply never got it changed. I sleep through it all the time, but my parents say they're tired of it and why don't I just rip it off the ceiling?!? Or at least replace the beeping with new batteries.
The fire alarm level/sudden smoke detector ring sometimes is just above my threshold of hearing. I suggest a new fire alarm be installed. Make sure the decibel level is up there.
Man you still have those sleeping problems? Sounds like me. Like I say, It happens. Shit happens. I read in articles that infants especially have hard times, they sleep through fire devices. Young parents can wake up to fire alarms but they're adults with maybe different physiology. It could be due to several things: faulty devices (doesn't sound like it, since inspectors checked yours), faulty physiology, faulty ears. Look into the other two. Talk to a real good doctor. Do you know that infants sleep 24 hours a day, prisoners sleep 15-16 hours, and average human needs 8 hours a day, but people with disorders , I think it's hypersomnia (opposite of insomnia) sleep closer to the 16-20 hr range. Hope you stay alive, it could be life and death condition in you getting burned. Talk to a real good doctor when you've lots of time and ready.