http://www.youtube.com/watch?v=RDn4e_8jqWk
Watch the speaker volume.
More tones to come!
EDIT: http://cjssirenforum.host56.com/Sirens/ for the 3 so far. 2 versions of Alert and one of Attack.
You'll have to right-click and save target as... to listen to them, unfortunatley.