On Wed, 13 Dec 2006, Hampton, Nathan E. wrote:

> “For each 3 dB increase in average noise level, the time you can safely
> stay at a level is halved. Thus, at 88 dB, it would take only 4 hours to
> reach the maximum allowable daily noise dose, at 91 dB it would take
> only 2 hours, and so on.” Given that the basis is 85dB, a 3dB increase
> is 3.5% increase and this 3.5% increase creates a half life of from 8
> hours to 4 hours in exposure? Bull.

Decibels are a logarithmic measurement of power (in this case sound
power).  Each 10dB multiplies the power by 10.  3dB is very close to 2x,
which is why stereo VU meters and equalizers (for example) are often
marked in 3dB increments.  So, doubling the sound power (+3dB) would half
the exposure time to reach some threshold.

J. Adam Butts
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