The unusual sound heard by pax could have been the flaps retracting, which without engines spooled up would probably be the most prominent and "not normally heard sound' at that point on the approach.
And considering the obvious technical prowess of most people here I am surprised that you have difficulty with the OFF mode for your PC/MAC when you don't like what you are reading instead of this persistent fascist approach of telling people what they can and can't write, think or do. Get a life eh?
Speculation or conjecture no matter how ridiculous is where discoveries and ideas come from, talk out the most ridiculous first and fine tune the way to the truth.
