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3. MEASUREMENT OF THE NOISE UNDER INVESTIGATION
3.1
General
the measure
noise under
investigation
in
The Authority should
accordance with the procedures outlined in Section 3.2. Corrections may need to be applied to the Measured Noise Level (MNL) to account for certain noticeable characteristics of the noise and these shall
be made in accordance with Section 3.3 to determine the Corrected
Noise Level (CNL).
Where the NSR is considered by the Authority to be materially
affected by one or more other noise sources falling within the scope
of this Technical Memorandum, the Authority shall assess the noise
under investigation in a manner which the Authority considers
appropriate in the circumstances,
to regard
acoustical principles and practices.
having
3.2 Determination of the Measured Noise Level (MNL)
standard
The MNL of the noise under investigation shall be measured over any 30 minute Sample Time Period (STP) by the Authority in accordance
with the calibration and measurement procedures detailed in the Annex. An adjustment may be made where appropriate to allow for the influence of the background noise, in accordance with standard
acoustical principles and practices.
3.3 Determination of the Corrected Noise Level (CNL)
3.3.1
General
Where the noise under investigation is considered by the Authority
to have tonal, impulsive or intermittent characteristics, appropriate corrections shall be made to the MNL to obtain the CNL,
as detailed below.
3.3.2
Correction for Tonality
A correction for tonality shall be applied if, between 25 Hz and 16 kHz, any one-third octave band or any pair of adjacent one-third
octave bands of the A-weighted spectrum of the noise
investigation satisfies all of the following conditions :-
under