When was the last time you checked the batteries in your smoke detectors?
Don't worry about silly thing like that. More worry about boom from partying lol.
China isn't Socialist. The USSR wasn't Socialist either. Some countries in Europe ARE Socialist, and some of them are still having severe economic problems so not even Socialism is a perfect economic model.
Fire alarms are pretty damn loud, so there's not really anything you can easily just throw over the cage like a blanket or something. The closest thing to sound-proofing that I can come up with would be to build an insulated, wooden box big enough to cover the cage that can be lifted over it. However, that's obviously quite cumbersome. In all honesty, if your friend is truly that worried that her rabbit's health may be at risk due to the fire alarms, I'd recommend she seriously consider giving the rabbit to a good home and getting a different pet.
