62 
08 
80 
75 
70 
60 
=| 
= 
5S 
50 
4s 
40 
35 
30 she 
25 ( 
20 — 
Ss 
10 
5 
° 
TECHNICAL SURVEY 
b=% 
b= 
EXAMPLES SHOWN BY DASHED LINES 
b=0 b= %, 
B= 3.75 4282410 
$=70 S$=7 
DB=64 DB=27 
Figure 7 
3.0 
35 
10.0 
TaBLEe 2. Work sheet for coverage diagram calculations. db = 46 (MIT — 95 db) » ‘me = 3,000 , ifme = 300,000 
Y = 13.9 hi = 100 ft 
k B n b a S C H 
1 0.21 1 3 0.478 53.5 —2.15 350 
2 0.42 1 4 0.581 82.5 —1,29 950 
3 0.63 1 3 0.655 93.0 — .20 1,350 
4 0.84 1 3 0.72 85.0 1.07 1,250 
5 1.02 1 y 0.778 52.5 2.45 600 
6 1.22 2 0 
7 1.35 2 2 0.828 56.0 4.10 750 
8 1.55 2 4 0.835 94.0 4.70 1,850 
9 1.85 2 3 0.863 109.0 5.70 2,550 
10 1.95 2 z 0.873 98.0 6.60 2,200 
11 all 2 $ 0.893 57.0 7.80 950 
12 2.3 3 0 
15 2.9 3 3 0.923 114.0 10.80 3,300 
21 3.9 4 4 0.951 118.0 15.40 4,100 
27 5.3 5 3 119.0 23.5 5,100 
he 
300 
908 
1,316 
1,222 
568 
733 
1,834 
2,536 
2,187 
939 
3,292 
4,095 
5,100 
