loadingTwo Sound Sources
Lp1= X dB
Lp2= X dB
Lp1+ Lp2= X + 3 dBBA 7666-11, 26
Addition of dB Levels
L+dB3Example:L1L2?LL+Lt=55 dB=51 dB=4 dB=1.4 dB=55 + 1.4 = 56.4 dB21.4 dB
100
4 dB
BA 7666-11, 27860512/2
51015
?LdB
Subtraction of Noise LevelsLS+N[dB]LN[dB]BA 7666-11, 28
Subtraction of dB Levels
L?dB654321
123456
7
8910LS ~ LS+N
?LdB
Ex:LS+NLN?LL?LS=60 dB=53 dB=7 dB=1 dB=60 ?1 = 59 dB??
BA 7666-11, 29
?
Addition of many dB values
Addition of sound levels :L1+ L2..... + LN = ?
For L1= L2= L3..... = LN
10 log N1210864200
BA 7666-11, 30
LTotal=L1+10logN
Examples:
N = 2: LTotal = L1 + 3 dBN = 10: LTotal = L1 + 10 dB
51015
N