Liz:

I think the device you described sounds like a great idea for one simple reason; People committing crimes generally don't like to attract much attention. The racket of a a 100 decibel noise maker along with the screams of "fire"* by the owner will make an assailant more likely to run.

* In the US, people are encouraged to yell "fire" if being attacked because it arouses the morbid curiousity of potential onlookers.


Chris