How do the cabin noise levels of the A380 and the 777 300 ER compare? I couldn't find any official comparison for noise level (dB) in Airbus A380 versus the Boeing 777 300 ER. Does anyone have some info about it? Which one is better in terms of acoustic isolation?
From a luxury round the world flight on several different models of aircraft on several different airlines, a traveler used the exact same sound meter at his seat in either business or first class to measure ambient noise level during cruise. 

Here is a chart I made of his measurements, including carrier and age of aircraft. As you can see, long haul aircraft are quieter than short. Carrier and age of aircraft also seem to make a difference. 

For this set of measurements, the b773 is 3db (or 25%) louder than the a380.