I feel like Airbus planes in general are much quieter than Boeing planes. I flew in a A320 from Bangkok - Singapore and Amsterdam - Moscow and both of these times the flight was much quieter then all of my other flights. Other flights included a diversity of (Boeing) planes including the 737, 747, 777 (300ER) and Embraer 190 (KLMs city hopper). I do usually sit in the front of the plane so it wasn't just the engine noise that was quieter.