Add to that that a huge amount of houses within the noise footprint of Heathrow have changed hands in the last 20-25 years as it, oddly enough, is one of the more affordable areas of London you have to think that they must have noticed the airport!
The noise insulation and, in many cases, triple glazing (both paid for by the Airport operator) coupled with the massive advances in engine noise technology (ironically the A380 'Behemoth' being the quietest!) has led to large reductions in the noise footprint as gathered by the noise monitoring stations.
We see this row of houses just off to the left as you come in over the farm for 27L. Those pictures needed some clever photography to produce those effects. Laterally we are a long way from the houses.
