WIRED: Heathrow is busier than ever, but physics means it's getting quieter

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In modern engines, “the fan generates a large portion of the total thrust, and helps reduce noise by virtue of lower exit speeds,” says Antonino Filippone, an aerodynamics researcher at the University of Manchester. Simply put, the less air that goes into the combustor, the quieter an engine tends to be. And most modern jet engines only channel about ten per cent of their total air intake into the combustor, making the whole engine a lot quieter.

And Filippone says that things will keep getting quieter. He predicts that the perceived level of engine noise will keep dropping by 1.5 decibels per decade. For residents around Heathrow, however, this good news comes with a big catch. More flights mean more noise, no matter how quiet planes are getting. And for people living in the two villages that stand to be demolished to make way for Heathrow’s third runway, there’s nothing but cold comfort in quieter engines.