I'm going LAX-SYD and AKL-LAX on a Qantas 747-400 in April and have wondered about the noise levels in Business. I recently noticed on a FRA-PHL flight on an A330 (US Airways) that some areas of the plane were much quieter than others. Oddly, I found the mid and rear on the A330 to be much quieter. I know that aerodynamics could be part of it, but also such factors as how many components of the HVAC systems are switched on etc. Note, I have read many posts about upstairs/downstairs based on spaciousness, level of personal service etc. I'm simply interested in your observations regarding the level of background white noise that is related to engines, HVAC and wind noise. TIA!