# The Air Navigation (Environmental Standards For Non-Part 21 Aircraft) Order 2008, Paragraph 3: Calculation of sound exposure level LAE from measured noise data


(1) The sound exposure level LAE is defined as the level, in decibels, of the time integral of squared ‘A’-weighted sound pressure (PA) over a given time period or event, with reference to the square of the standard reference sound pressure (Po) of 20 micropascals (P) and a reference duration of one second.
(2) This unit is defined by the expression—
where To is the reference integration time of one second and (t2 - t1) is the integration time interval.
(3) The above integral can also be expressed as—
where LA(t) is the time varying ‘A’-weighted sound level.
(4) The integration time (t2 - t1) in practice must not be less than the time interval during which LA(t) first rises to within 10dB(A) of its maximum value (LAmax) and last falls below a level of 10dB(A) less than its maximum value.
(5) The LAE may be approximated by the following expression for LAmax—
LAE=LAmax+ΔAwhere ΔA is the duration allowance given by ΔA = 10 log τ where τ = (t2-t1)/2.

---
Source: https://www.legislation.gov.uk/uksi/2008/3133/schedule/part/2/paragraph/3 (the official version)
Page: https://openlegislation.uk/air-navigation-environmental-standards-for-non-part-21-aircraft-order-2008/schedule/part-2/paragraph-3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.