Something interesting...

I was watching a Portal 2 video recently, and at one point I hear what sound like familiar sounds in the background. I listen several more times, and I can make out what sounds like a Simplex Truealert and some sort of mechanical horn sounding in the background! Dug through the game files, and sure enough: there are at least several ambient sound files that DO sound like fire alarms! The Truealert-sounding one (amb_random_tech_15) sounds almost IDENTICAL to the actual sound of a Truealert I’d say, more specifically one or more Truealerts being sounded twice in quick succession. Haven’t been able to nail down a make or model on the mechanical horn-esque sound. (amb_randabstract_hi_10) There’s also another sound file (amb_random_tech_03) that ALSO sounds like a mechanical horn with a loose diaphragm being sounded VERY briefly.
Some other fire alarm-sounding ambient sound files:
amb_random_tech_05, which almost sounds like a bell’s gong being hit
amb_random_tech_13, which sounds like a fairly large alarm bell ringing for a split second
amb_random_tech_14, another bell-sounding ambience file
amb_randabstract_hi_06, sounds like some kind of alarm though I can’t lay my finger on it exactly
As far as the rest of you hearing the sound files, I don’t know of where they could be listened to online, but if you have the game you can use GCFScape to access the sound files. They’re located under sound/ambient/random_abstract. Have a listen for yourself and tell me what you think. (wonder if Valve knew about the one file basically sounding identical to a Truealert)