### Strutt Help

Mechanical Services Calculation Sheet    1/1

Strutt|Blank Sheets|Mechanical inserts a blank mechanical services Strutt calculation sheet into the current workbook.

The sheet includes columns for duct insertion losses or attenuation, as well as columns for regenerated noise levels.

A set of 'Cumulative Sound Power Level' columns keeps track of the down-duct sound power after each row:

L_(W,i)=10log(10^((L_(W,i-1)+IL_i)/10)+10^(L_("W,regen,i")/10))

where:
L_(W,i) is the sound power level immediately downstream of row i of the worksheet
L_(W,i-1) is the sound power level immediately downstream of the previous row (i-1) of the worksheet
IL_i is the insertion loss of the element in row i of the worksheet
L_("W,regen,i") is the sound power level generated by the element in row i of the worksheet

(Note references to 'downstream' refer to the direction that sound is propagating along the duct, i.e. from source to receiver)

The final down-duct sound power levels are used for a room noise level calculation, including both the reverberant level and the direct level.
The source directivity is pre-filled using the Internal Outlet Directivity calculation for convenience, but may be modified by the user as desired.

This function can also be accessed by right-clicking on the ply (the set of tabs at the bottom of the Excel window with the sheet names), using the Context-Sensitive Menus