IIRC the buzz saw sound is - and I stand to be corrected by any of my more learned brethren on here - the pressure waves caused by the tips of the fanblades on the front disk going supersonic. The buzzsaw sound only happens at high thrust settings ie: takeoff.
So why would a C17 not create the buzzsaw noise? No idea - it has four PW2000s, right? Heard them go buzzing many times on PW
-powered 757s so it cant be the engine.
Perhaps a derated takeoff, or maybe some degree of acoustic or thermal shielding on the cowlings and exhaust that the 757 doesnt have?
What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???