### Strutt Help

Noise Transfer (Inside to Outside)
**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

Comments or suggestions to
strutt@arup.com