Grew up next to LHR in 60s and some familiar candidates here
Caravelle was phenomenally loud for two engines -mind you the Lightening had two Avons as well- but the Caravelle was always noisier than a Coment with four of the same jets
Trident 3 made a cool noise with the boost jet of course and VC10 very very loud
A different type of noise was the approach 'scream' of the fan engined Seven ohs and DC8s. There used to be a Cinema in Hounslow right under the 28R approach and they drowned out the loudest film
As Pax I flew on all of the above except the Caravelle and of course all the Brit contingent were rear engined so fine for the select few on board and too bad for the plebs outside ( very Brit approach)
For interioir noise I would have to go for the behind the wing seats on a non fan 707 or even worse the RR Conway engined DC 8. Even with the extraordinary giant movable 'silencers' that ran on rails behind the engines this was spectacular. I flew on an Alitalia one of these and to this day it sticks in my mind as the loudest plane ever.
Great thread -imagine a 777 with noise scaled up along with the engine size from a sixties jet LOL
PB