Decibels (16.8)Comparing sound intensities

• The intensity level b (expressed in decibels) of a sound with intensity I relative to a sound at the threshold of hearing I0 = 10-12 W/m2 is

b (in decibels) = 10 log (I/I0)

log denotes the logarithm to base 10

• b is unitless and not an intensity  b=0 means that I=I0 and not that I=0

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