Re aircraft noise.
A simple non scientific impressive test on how noise levels have and will continue to be lowered.
Heathrow expansion: Plane spotters take 'blind test' - BBC News
A few days ago one of the many Heathrow departures that fly over my home caused me to look up. It was a BA Dreamliner. it was so quiet compared with others.
Perhaps the population of London and surrounds should view this video clip.