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3.3.3
Correction for Impulsiveness
If the noise under investigation is considered by the Authority to be impulsive in character a positive correction, Cimp, of not more than
3 dB(A) may be applied to the MNL.
3.3.4
Correction for Intermittency
A correction for intermittency shall be applied to the MNL, for the night-time period (2200 to 0700 hours) only, when the A-weighted sound pressure level of the noise under investigation is subject to rapid changes in level of 5.0 dB or more occuring with a degree of regularity within the STP, the typical magnitude of these changes in level being known as the intermittency factor, f fint.
Where the noise under
intermittent characteristic
investigation is assessed to have an
with an intermittency factor, f
correction, Cint' to the MNL shall be as shown in Table 5.
the
int'
|
Table 5
Intermittency Correction
fint (dB)
| Cint (dB(A))
greater than or equal to 5.0 and less than 10.0
3
6
greate
greater than or equal to 10.0
3.3.5
Calculation of Corrected Noise Level (CNL)
The CNL shall be calculated by applying the appropriate corrections to the MNL in accordance with the following formula :-
CNL
MNL
+
Ctone
Simp
Cint
dB(A)