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Sound Engineering for Aircraft


SEFA is the first project using sound engineering practices to define optimum aircraft noise shapes (target sounds). It is a unique and innovative approach for exterior aircraft noise control as it considers human factors as well as technical factors.

Project objectives

The project objectives are:

  • To establish scientifically how the noise annoyance of aircraft can be reduced, not just by lowering noise levels but also by improving the characteristics of aircraft noise signatures.
  • To develop optimum aircraft noise shapes based on a sound quality approach, together with simulation tools capable of adjusting to future technology developments and improvements in the understanding of noise impact.
  • To use these findings and tools in setting up sound engineering design criteria for optimum exploitation of novel noise reduction technologies, innovative aircraft and engine architectures, and extended operational capabilities.

Description of the work

Aiming at the development of sound engineering design criteria for future aircraft, the project will go through successive phases that can be summarily described as specification (Work Package 1), understanding (Work Package 2), optimisation (Work Packages 3-5) and definition of design criteria (Work Package 6).

Work Package 2 is hereby playing a major role in performing the required listening tests. The test results are providing baseline information for the design of an optimised target sound and the formulation of the related design criteria for aircraft.

On top of the Work Package 2 tests, Work Package 5 is analysing the notion of annoyance and its links to aircraft noise and is developing a tool simulating the subjective perception of residents regarding aircraft noise.

Work Package 3 is analysing current aircraft sound shapes and generating optimised target sounds. These target sounds are validated again by psychometric tests (Work Package 2).

Work Package 4 is analysing the aircraft sound shapes with respect to individual source characteristics and is developing a tool, which provides audible sound tracks for virtual aircraft configurations. This tool will provide a feedback loop from the optimised target sounds to the aircraft sources and flight procedures. It will be applied by Work Package 6 in the final definition of design criteria for aircraft.

Expected results

The major output of the programme is the definition of aircraft design criteria based on a validated target sound design procedure. In addition, SEFA will provide the valuable assessment of the human-specified characteristics of aircraft sounds by analytical and statistical methods, as well as a basic tool providing audible fly-over sounds for virtual aircraft configurations.