I learned some things this morning! For instance, according to the smoke alarm in our bedroom, steam from my shower is now the same thing as smoke. Also, said smoke alarm does not have the "BEEP BEEP BEEP BEEP" sound characteristic of most smoke alarms. Our smoke alarm instead makes a noise more like "BRRRRRRRRRRRRRRROOOOOOOOOOOWWWWWWWWWWWWWWWWWWWRRRRRRRRRRRRRRRRRRRRRRRRRRRR". Only much, much louder. It is sort of like if you took an old-timey alarm clock and made it very angry, and then amplified it and shoved it in my ceiling. It is a death from above, the ceiling is trying to kill me sort of noise.
For all that this noise is far more likely to get you up and out of bed than the standard beep, it does not say "fire alarm". Thus I jumped out of the shower, water still running, and ran around the bedroom dripping water and yelling about what the hell was going on and what that horrible sound was. Luckily, Charlie has today off, and while I threw clothes on to be safe, he was all having his glasses on able to determine that the horrible noise was the smoke alarm and that the building was not on fire.
And everything is fine now. The smoke alarm stopped by itself (which is good, as we can't reach it even on a stool and would have had to whack it down with a broom). Once we calmed down, we realized that we live around the corner from the firehouse, so if the building was on fire we would know by now.
Also, I've learned that the likelyhood of my ever sleeping through the smoke alarm is basically nill.