COMPUTATION OF THE COMPOSITE NOISE 



617 



components may be carried out with this chart by first adding two 

 components, then adding the resultant to a third component and con- 

 tinuing until all components have been summed up. Incidentally, 



-8 -10 -12 -14 -16 -18 

 i = LOGARITHMIC WEIGHT FACTOR 



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Fig. 4 — Relation between peaks per minute (w,) produced by a noise source 

 and its logarithmic weight factor (Wj). 



the chart shows that the contribution to the composite noise from a 

 source whose weighted intensity {Ai -\- Wi) is 20 db or further below 

 that of another noise source {A% -\- w^) is negligible. 



