Hey! I flew on jetBlue for the first time last week and it was also my first time on an A320. While we were at the gate, just before pushback, there was a real high pitched squeal that rang through the cabin for about 8-10 seconds. What was this noise? Is this noise unique to jetBlue or A320s in general? Because I don't remember hearing this on any other type of aircraft. Haha, maybe its on all aircraft and I just haven't noticed it. Thanks! <font color="blue"> </font>