TaBLE 1. Intensity increments resulting from mixture of two tones of the same frequency
and in the same phase but with differing intensity levels.*

dB diff.
between L i+ Lt+kh Lith i
Trand Ty i, L log Tr 20 log 7 Al in dB
0 1, 0000 2, 0000 0. 30103 6, 0206 6. 0206
1 1, 1220 2, 1220 0, 32675 6. 5350 5. 5350
2 1. 2589 2, 2589 0. 35390 7. 0780 5, 0780
3 1, 4125 2, 4125 0. 38247 7. 6494 4, 6494
4 1, 5849 2, 5849 0, 41244 8. 2488 4, 2488
¢ 1. 7783 2. 7783 0. 44378 8. 8756 3, 8756
6 1, 9953 2, 9953. 0, 47644 9, 5288 3. 5288
7 2. 2387 3. 2387 0. 51037 10, 2074 3. 2074
8 2. 5119 3.5119 0, 54554 10. 9108 2. 9108
9 2. 8184 38, 8184 0, 58188 11. 6376 2. 6376
10 3. 1623 4, 1623 0. 61933 12, 3866 2. 3866
i 3. 5482 4, 5482 0. 65784 13. 1568 2. 1568
12 3. 9811 4, 9811 0. 69733 18, 9466 1, 9466
13 4, 4668 5, 4668 0. 73773 14, 7546 1, 7546
14 5. 0119 6. 0119 0. 77901 15. 5802 1, 5802
15 5. 6234 6. 6234 0, 82108 16. 4216 1, 4216
16 6. 3096 7, 3096 0. 86390 17. 2780 1, 2780
7 7. 0795 8. 0795 0, 907385 18. 1477 1.1477
18 7, 9433 8, 9433 0. 951495 19. 0299 1, 0299
19 8. 9125 9. 9125 0, 996185. 19, 9237 0. 9237
20 10. 0000 11, 0000 1. 0413927 20. 827854 0, 827854
21 11. 220 12, 220 1. 08707 21. 7414 0. 7414
22 12. 589 13, 589 1, 13319 22. 6638 0. 6638
23 14, 125 15, 125 1, 179695 23, 5939 0. 5939
24 15, 849 16. 849 1, 22657 24. 5314 0, 5814
25 17. 783 18. 783 1. 27377 25, 4754 0, 4754
26 19, 953 20, 953 1, 32124 26, 4248 0. 4248
27 22, 387 23, 387 1, 36897 27. 3794 0, 3794
28 25. 119 26. 119 1.41695 28. 3390 0, 3390
29 28, 184 29, 184 1, 46515 29. 3030 0. 3030
30 31, 623 32. 623 1. 51352 30. 2704 0. 2704
31 35, 482 36. 482 1. 56207 31. 2414 0, 2414
32 39. 811 40. 811 1, 61078 32, 2156 0. 2156
33 44. 668 45, 668 1. 65961 33, 1922 0. 1922
34 50. 119 51.119 1, 70858 34, 1716 0. 1716
35 56. 234 57, 234 1. 75765 35, 1530 0, 1530
36 63, 096 64, 096 1. 80683 36, 1366 0. 1366
37 70. 795 71. 795 1. 85609 37, 1218 0. 1218
38 79, 433 80. 433 1, 905435 38. 1087 0. 1087
39 89, 125 90. 125 1. 954845 39, 0969 0, 0969
40 100. 000 101. 000 2, 0043214 40. 086428 0, 086428
Al 112, 20 113, 20 2, 05385 41, 0770 0. 0770
42 125. 89 126. 89 2. 10343 42. 0686 0. 0686
43 141, 25 142, 25 2. 15305 43. 0610 0. 0610
44 158, 49 159, 49 2, 20273 44. 0546 0. 0546
45, 177. 83 178. 83 2, 25244 45, 0488 0, 0488
46 199, 53 200. 53 2, 30218 46. 0436 0, 0436
47 223. 87 224. 87 2, 35193 47. 0386 0, 0386
48 251. 19 252. 19 2, 40173 48. 0346 0. 0346
49 281. 84 282, 84 2. 45154 49. 0308 0. 0308
50 316. 23 317. 23 2, 50137 50, 0274 0. 0274
51 354. 82 355. 82 2. 55123 51. 0246 0. 0246
52 398. 11 399, 11 2. 60109 52. 0218 0. 0218
53 446. 68 447. 68 2, 65097 53. 0194 0. 0104
54 501. 19 502. 19 2. 70087 54, 0174 0. 0174
55 562. 34 563. 34 2. 75077 55, 0154 0, 0154
56 630. 96 631. 96 2. 80069 56. 0138 0. 0138
57 707. 95. 708. 95 2. 850615 57. 0123 0, 0123
58 794. 33 795. 33 2. 90055 58. 0110 0.0110
59 891, 25 892, 25 2. 950485 59, 0097 0. 0097
60 1000. 00 1001. 00 3. 0004341 60. 008682 0. 008682

* Al is the decibel difference between I; and (i+I,), where I, is the greater and Ip is the
lesser intensity.

2 GPO : 1986 0 - 224-076


AM 66-4

A TABLE OF INTENSITY INCREMENTS

Jerry V. Tobias, Ph. D.

Approved by Released by
J. Rosert Dittx, M.D. P. V. Sicrn, M.D.

Curr, Crvm, Arromepicat InstiruTe Feprrat Arr Surceon

January 1966

FEDERAL AVIATION AGENCY
Office of Aviation Medicine



Qualified requestors may obtain Aviation Medical Reports from Defense Documentation
Center. The general public may purchase from Clearinghouse for Federal Scientific and
Technical Information, U.S. Dept. of Commerce, Springfield, Va. 22151


A TABLE OF INTENSITY INCREMENTS

Occasionally one needs to compute the sizes
of increments produced by adding two signals
that differ only in amplitude (Figure 1). Nor-
mal procedure seems to require that the caleu-
lations be performed anew each time someone
wants to add two signals. Recently I had to
add some tones again and decided to complete
a table of values one might encounter using
1-dB/step attenuators. So that no one need go
through the arithmetic again unless he really
wants to, here is the table (Table 1). Inter-
mediate computational steps are included be-
cause their values are sometimes also useful.

Anyone who works with the table should be
cautioned that meter readings for nonsinusoidal
signals may not agree with the tabulated val-
ues; a true-rms meter will solve that problem.
Also, he must not trust these values unless he
has devised an extremely accurate adding sys-
tem and has insured that cross-channel leakage
is as close to zero as possible. Finally, he must
remember that any data he gathers will be just
as inaccurate and variable as any other data
despite the false sense of precision he feels from
using values that look to be correct to the nth
significant figure.

Signal
Source

mi

hyo

Mixing
Network
(Adder)

Attenuator

|__| /-dB-per-step

le

>

Fiaure 1.

(i, lo, & Al in dB)

Simplified block diagram.