Decibel levels
QUESTION:
The decibel level of a jackhammer is 130 dB relative to the threshold of hearing.
[1x10
-12 Wm
-2 ].
Determine the decibel level if TWO jackhammers
operate side by side.
Answer:
The defining equation for decibel levels is:
dB = 10
log(Intensity 1/Intensity at threshold)
For one jack hammer this is 130 dB and so
solving this
130 = 10 x log(Intensity 1/1x10
-12) 13 = log(Intensity
1/1x10
-12)
Intensity for one jackhammer (Intensity 1) = 10 Wm
-
2.
For two jackhammers the intensity would be 20 Wm
-
2.
Therefore dB level = 10 x log(2x10/1x10
-12) = 10 x
log(2x10
13) = 133 dB.
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