The 380 cabin is really quiet. It is an amazing difference when compared to the 744. The QF 380 F cabin is far enough away from the most noise prone parts of the airframe (ie the very front) and indeed, even the front of Business is delightfully quiet. Across the range of aircraft, Airbus is consistently quieter than Boeing (type for type and position for position). Engine noise is a non issue.
IIRC the A340 (500-600) were the exception and required a realignment of engines to make it quieter.
Boeing seem to think the way to reduce weight (and make the performance guarantees) is to reduce the noise insulation and state that passengers do not like quieter cabins. I have also been told that the insulation on the 777 has een reduced in thinkness to assist with the installation of 10 across seating in WHY.