Concept:
is that the statistical value of sound pressure level that can be equated to any fluctuating noise. Thus, is defined as the constant noise level, which over a given time, expand the same amount of energy, as it expanded by the fluctuating levels over the same time.
The value of can be expressed as
Where n = Total number of sound samples
Li = The noise level of any ith sample
ti = Time duration of the ith sample expressed as a fraction of total sample time.
Calculation
Given,
noise levels 60, 69, 70, and 79 dB
As time is not mentioned assume all noise lasts from start to end of duration T
∴ ti = T/T = 1
Now,
= 79.9 dB
Note: The equivalent sound level for the group of sound levels will be near to the highest sound level ( here its 79 dB )
