Commission Directive (EU) 2015/996 of 19 May 2015 establishing common noise assessment methods according to Directive 2002/49/EC of the European Parliament and of the Council (Text with EEA relevance)
When the UK left the EU, legislation.gov.uk published EU legislation that had been published by the EU up to IP completion day (31 December 2020 11.00 p.m.). On legislation.gov.uk, these items of legislation are kept up-to-date with any amendments made by the UK since then.
EU Directives are published on this site to aid cross referencing from UK legislation. Since IP completion day (31 December 2020 11.00 p.m.) no amendments have been applied to this version.
The basic concept of the energy fraction is to express the noise exposure E produced at the observer position from a flight path segment P1P2 (with a start-point P1 and an end-point P2 ) by multiplying the exposure E∞ from the whole infinite path flyby by a simple factor — the energy fraction factor F:
| E = F · E∞ | (E-1) |
Since the exposure can be expressed in terms of the time-integral of the mean-square (weighted) sound pressure level, i.e.
to calculate E, the mean-square pressure has to be expressed as a function of the known geometric and operational parameters. For a 90° dipole source,
where p 2 and pp 2 are the observed mean-square sound pressures produced by the aircraft as it passes points P and Pp .
This relatively simple relationship has been found to provide a good simulation of jet aircraft noise, even though the real mechanisms involved are extremely complex. The term dp 2/d2 in equation E-3 describes just the mechanism of spherical spreading appropriate to a point source, an infinite sound speed and a uniform, non-dissipative atmosphere. All other physical effects — source directivity, finite sound speed, atmospheric absorption, Doppler-shift etc. — are implicitly covered by the sin2ψ term. This factor causes the mean square pressure to decrease inversely as d4 ; whence the expression ‘fourth power’ source.
Introducing the substitutions
the mean-square pressure can be expressed as a function of time (again disregarding sound propagation time):
Putting this into equation (E-2) and performing the substitution
the sound exposure at the observer from the flypast between the time interval [τ1 ,τ2 ] can be expressed as
The solution of this integral is:
Integration over the interval [–∞,+∞] (i.e. over the whole infinite flight path) yields the following expression for the total exposure E∞ :
and hence the energy fraction according to equation E-1 is
The Whole Directive you have selected contains over 200 provisions and might take some time to download. You may also experience some issues with your browser, such as an alert box that a script is taking a long time to run.
Would you like to continue?
The Schedules you have selected contains over 200 provisions and might take some time to download. You may also experience some issues with your browser, such as an alert box that a script is taking a long time to run.
Would you like to continue?
All content is available under the Open Government Licence v3.0 except where otherwise stated. This site additionally contains content derived from EUR-Lex, reused under the terms of the Commission Decision 2011/833/EU on the reuse of documents from the EU institutions. For more information see the EUR-Lex public statement on re-use.
