Noise Pollution Level (LNP) Calculator
The noise pollution level (LNP) is an evaluation of noise given by combining the influence of both energy average and variation characteristics (expressed by standard deviation). The noise pollution level (LNP) is an evaluation of noise given by combining the influence of both energy average and variation characteristics (expressed by standard deviation).
Many non-steady-state noise practices have shown that the degree of annoyance caused by fluctuating noise is greater than that of steady-state noise of equal energy, and is related to the rate of change and average intensity of noise exposure. Experiments have shown that adding a quantity representing the amplitude of noise variation on the basis of the equivalent continuous sound level can better reflect the actual degree of pollution. It is more appropriate to use this noise pollution level to evaluate aviation or road traffic noise. Therefore, the noise pollution level (LNP) formula is:
LNP = Leq + Kσ
Where:
K —— constant, 2.56 for traffic and aircraft noise;
σ —— standard deviation of instantaneous sound level during measurement.
Where: Leq is the equivalent sound level; σ is the standard deviation.
If the noise follows a Gaussian distribution, then LNP=L50+d+d^2/60
Where: d=L10-L90; L10 is the A sound level that occurs more than 10% of the time or frequency during the measurement period, and the rest is analogous.
Noise Pollution Level (LNP)
Noise Pollution Level (LNP) calculation = L50+L10－L90+（L10－
L90)2/60
Here
NPL = Noise Pollution Level
L10 = 10% or more of the time of A sound level
L50 = 50% or more of the time of A sound level
L90 = 90% or more of the time of A sound level