Experts found people exposed to 60 decibels of jet noise for three years were twice as likely to have high blood pressure.

However, it said that sustained growth since 2009 had led to more people being exposed to jet noise around several airports.

Engine handling and low jet noise are facilitated by the use of a variable area final nozzle, to rematch the fan.

The lower exhaust speed also gives much lower jet noise.

There were issues with tip jet noise, and the program was cancelled in 2008.