I still haven't found any laws written anywhere dictating if or how/when a citizen can blow a siren from a house. Definitely it's illegal to have a siren on a car, but outdoor sirens have nothing in the books as far as I have found. I have a copy of the CA Penal and Civil Codes, and I did a lot of reading. I've also searched the Net. The only laws that would apply would be disturbing the peace, and no violations there since noise is allowed until 10PM in most places.
There could be a federal law, but I don't know where to look. Even if so, out here in Moorpark there are people doing target shooting, unlicensed pilots flying airplanes from un-official landing strips, and all kinds of things that you couldn't do in cities.
Charles