Strutt|Building Acoustics|Inside to Outside Noise Transfer calculates the external noise level at a certain distance (R) from a facade, given the internal sound pressure level, the transmission loss (TL) and the area of the building envelope facing the receiver (S), and inserts the result into the active row of the worksheet.
Strutt implements the calculation using the following formula:
`L_(p,out) = L_(p,i n) + TL + 10log_10(S) - 20log_10(R) - 14`
This calculation assumes hemispherical radiation and point source, and so is only valid for distances greater than 3 times the major source dimension. Any further corrections for sound reflection should be applied by the user.
Reference: Acoustics, Noise and Buildings (Fourth Edition), Parkin, Humphries and Cowell, p238