We flew a few times with my son when he was young and its always been stress free. He hated loud noises too but by the time the plane took off he was generally tired... I fed him during taxiing, then cuddled him to me chest to chest with his dummy and he woudl always fall asleep as soon as the roar of take-off happened! Crazy for a child who hated loud noise!

Obviously on a longer flight he wont sleep the whole time but I'm sure you'll cope... it's good you have someone travelling with you.

I always used a carrier in the airport too but didn't bother on the plane. Just held him in my lap.