I've been meaning to ask a question about these sirens. My understanding is that many electronic sirens use a recording of a mechanical siren when sounding off tornado or air raid alerts. My question is when they are winding up and winding down, is it the recording that is starting and finishing, or do the siren operators have some sort of manual fader control that can windup or wind down the sirens' blaring?
http://youtube.com/watch?v=W03SCw3lB8I