Question 83004
The loudness of sound is based on intensity level measured in decibels using a logarithmic scale and is relative to (a ratio of) the weakest sound the ear can hear.
I need the formula for measuring sound and pick a specific sound (a jet's sound when taking off) give the decibels of the sound, and explain what this measurement means.
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The decibel formula for sound intensity:
D = 10*log{{{(I/Io)}}}
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Where Io = 10^-12 which is the threshold of hearing (usually, the reference)
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The formula gives the decibel value of I, compared to Io
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An algebra book that I have gives the sound intensity of a jet with afterburner as:
     8.3*10^2
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Using the above formula where:
Io = 10^-12
I = 8.3*10^2
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D = 10*log{{{((8.3*10^2)/(10^-12))}}} = 10*log{{{(.83*10^(2+12))}}} add the exponents here
D = 10*log{{{(.83*10^14)}}}  = 10*log{{{(8.3*10^13)}}}
Find the log of 8.3(10^13) on a calculator
D = 10 * 13.919
D = 139.92 decibels 
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The ear has an incredible range the loudest sound that a person can hear without
damage to his ear, is 1,000,000,000,000 times the softest sound he can hear.
It's more convenient to use a logarithmic scale when dealing with big numbers
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I (intensity) is actually the sound measured in watts per square meter
Here's a few more:
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Whisper: 5.2*10^-10
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Heavy traffic: 8.5*10^-4
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Jackhammer: 3.2*10^-3
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The threshold of pain: 1*10^0
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They don't give one for obscene rap music, the threshold of pain has to be close
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Anyway, did this help you?