Check out this weird diaphone from Weaverville, California. I have never heard one quite like this. It must be operating on low pressure, or maybe there is something inside the piston, because it sounds obscene. My friend recorded it for me and he was about a quarter mile away. The siren, which I believe is a Darley, is on another building closer to his apartment where he recorded this noon test.
http://media.putfile.com/Weaverville-diaphone