### Strutt Help

Plantroom Noise Breakout

Strutt|Building Acoustics|Noise Breakout from Room calculates in the active row the sound power radiated from a plantroom, given the common surface area S of the plantroom and receiving room and the transmision loss TL of the partition.

Strutt calculates the noise breakout using the following formula:

L_(W,rad) = L_(p,rev) + TL + 10log_10(S) - Cd

Where:
Cd is -6 dB

EN 12354-4:2000 Annex B diffusivity terms

The above formula assumes a perfectly diffuse field. The user also has the option of modifying the above formula to utilise the diffusivity terms given in EN 12354-4:2000 Annex B as follows:

• Cd is -6 dB for relatively small, uniformly shaped rooms (diffuse field); in front of reflecting surface
• Cd is -3 dB for relatively small, uniformly shaped rooms (diffuse field); in front of absorbing surface
• Cd is -5 dB for large flat or long halls, many sources (average industrial building); in front of reflecting surface
• Cd is -3 dB for industrial building, few dominating directional sources; in front of reflecting surface
• Cd is 0 dB for industrial building, few dominating directional sources; in front of absorbing surface

References:

• Bies and Hansen (2nd Edition) p 208 - 209
• EN 12354-4:2000 Annex B