The swiss have some really strange sirens. The KTGs.
They were built by Kockum Sonics of Sweden, but as far as I know, only the swiss use them. They consist of different air horns.
Unfortunately I was not able to find out, what KTG stands for, but I do know, that the number behind the "KTG" stands for the number of horns attached.
They will be replaced by electronic sirens, during the next years.
They sound really strange, like a dying elephant, or a bunch of fully drunk trumpeters. Someone told me, that a siren doesn`t have to sound nice, but to catch the people`s attention. I`m pretty sure, it does.
So, here`s one of those dying elephants:
http://www.youtube.com/watch?v=IZFENE83ARo