For millions of people around the world, the unwelcome and often deafening intrusion of jet aircraft roaring overhead is a daily annoyance.
More than that, the stress it causes is increasingly being associated with physical and mental health problems.
© Fotolia, 2012
The problem is not confined to those who live in close proximity to an airport. People living miles away but under the take-off or landing paths can find their lives similarly plagued. So, also, can those who live under the areas where aircraft are kept 'stacked' as they wait to land at ever more busy airports.
At the same time, the demand for aviation, both from private consumers and from businesses, is growing rapidly. The inexorable move towards more and more flights (and more and more airports or runways), means the need to find ways of making aeroplanes significantly quieter is an urgent one.
Aircraft noise is caused by two things. One is the air rushing over the aircraft fuselage and its wings. The other is the noise from the jet engines. Although it may be hard to believe, progress has been made over the years in reducing this noise. Modern aircraft are quieter than their predecessors of 20 or 30 years ago. But there is still a long way to go.
Previous efforts at noise reduction have all focused on isolated aspects of the problem. But a large-scale project set up and largely funded by the European Commission is aiming to revolutionise the way that the modern blight of aviation noise pollution is tackled.
Involving 47 partners worldwide, including major players in the aeronautics field such Dassault, Rolls Royce, Volvo Aero and EADS, the 'OPENAIR' project is focused on taking a holistic view of the aircraft.
Rather than looking, for example, at the engine fan blades or the wingtips on their own, OPENAIR was set up with the specific purpose of taking a whole aircraft approach. In this way, it is able to take the interaction between all the different parts into account. Using a complex model that has been developed as part of the project, it is possible to assess the real effects as perceived by people on the ground when the aircraft is flown in 'real' life.
The 18 million euro project is using the latest techniques in computer analysis of the ways in which air flows behave and how aerodynamic forces interact with surfaces to create noise. With 15 months still to go of the four-year life of the project, large-scale testing of a number of new technologies and methods is well under way.
Key to the project's success is the unique collaboration it has been able to generate between a range of organisations across Europe. This has been the crucial factor enabling the researchers to take a holistic view of the issue and to develop techniques which make it possible not just to know what noise reduction is achieved at, for example, a wing tip, but to measure the total effect people on the ground would actually be hearing if an aircraft were flying overhead.
Given the extensive participation in the project of major players from the aviation industry, any positive results should be quickly implemented in future aircraft construction, as well as being retro-fitted where possible on existing aircraft.
It is hoped that the results will make major contribution to the aviation industry's official goal of reducing aviation noise by 50% by 2020, compared with the year 2000.