4.—(1) Any strategic noise map made or revised under this Part must satisfy the applicable requirements in Schedule 1.
(2) A competent authority under regulation 6 or 10 must apply—
(a)the noise indicators Lden and Lnight as referred to in Annex I of the Directive; and
(b)the supplementary noise indicators in all cases listed as examples in paragraph 3 of Annex I of the Directive,
when making or revising strategic noise maps under this Part.
(3) The values of Lden, Lnight and the supplementary noise indicators must be determined by means of the assessment methods set out in Schedule 2.
(4) Subject to paragraph (5) existing noise indicators and related data may be converted into Lden and Lnight.
(5) The data referred to in paragraph (4) must not be more than three years old.
(6) “Supplementary noise indicator” means a noise indicator as defined in Schedule 3.