Originally Posted by onobond

The noise measured outside the aircraft, especially at take-off and landing, may not be proportional to the noise level in the cabin, between different aircraft. This is due to many factors, such as number of decks, cabin design and material choice for surfaces whithin cabins.

Haven't seen intra-cabin sound level measurements comparisons, but for sure there are differences depending on where you are seated. Not doubting the alleged high noise outside a 747 at take-off over LHR, the intra-cabin variations are certainly large. Wheras for example 1A/K is less noisy than most seats in CW on UD, seats behind the wings/engines on main deck have another background noise level.

It would be a a great help for many in chosing flights, if a magazine like Business Traveller (or equivalent) could bring along and make public the various intra-cabin sound levels. Sort of in-flight sound check