COMPUTATION OF THE COMPOSITE NOISE 



615 



This equation can also be written 



I M m\ Ii , nil In 



_ nil Ii ^2 ^2 I mn In 



(5b) 



Equation (5b) is somewhat more convenient in computing than (5a). 

 In this equation a weight factor is associated with each intensity ratio, 

 which is in each case the actual number of peaks divided by the 

 maximum possible number of peaks. 



^-4 

 O 



(0 LU 



5 6 



QO 



1 1.5 2 3 4 5 6 7 8 9 10 15 20 30 40 50 



DISTANCE BETWEEN OBSERVER AND NOISE SOURCE IN FEET 



Fig. 3 — Loss of intensity with distance from noise source for various 

 amounts of room absorption. 



Assuming that the intensity corresponding to the average of the 

 db distribution of each source may be used, the following relations 

 exist for the source noises in db sound level : 



Ai = 101o£ 



/i 



A-i = 10 logio-p 

 -to 



An = lOlogio-y? 



(6) 



