ⓘ
This calculation is used to estimate the diffuse and direct sound level from the acoustic power
level of a source.
The formula for the calculation of the Lden:
\[
Lp_{total} =L_{w} + 10 \log_{10} \left( \frac{Q}{4 \times \pi \times r²} +
\frac{4}{R}\right)
\]
- R is called the room constant is calculated following \[
R =\frac{S \times \alpha_{mean}}{1 - \alpha_{mean}} \]
This calculation is validated in diffuse field condition. The modal aspect of the room is not taken
into
account.
The Schroeder Frequency (fs) is calculated with :
\[fs =2000 \times \sqrt{\frac{T}{V}} \]
With T the reverbertion time (in this calculation the T is the mean on all the frequency range) and V the
volume
Reference : Engineering Noise Control - Theory and Pratice - Bies
