Paxboy - I travelled CDG-JNB earlier this year on AF A380. Outbound was upstairs, return was downstairs. Have to say I didn't notice a difference in the noise level. Extremely quiet on both decks (eerily quiet as has been mentioned earlier).
As for the T7, I have to agree with previous posters that the noise is noticeably higher than other types. Really starts to grate on longer sectors (10 hrs +). Would rather be on B747, A380 or even A340 on long flights, however the economics make the T7 just too attractive to the airlines.