What a can of worms!
So there are two ways of computing. One for generation of the Mach # and one for the s.o.s..
I guess I was kinda on the right track... where it was going I'm not really sure. (I think it was heading for one of my physics books.) Sorry for doubting those in the know.
Oh well. Learn something new every day!

mtthomps, still want to do the experiment with the keg? I'm up for it!

By the way, since I haven't made it to my physics book yet, how does one convert Celcius to Kelvin? Is Hobbes involved?