"The C-weighting scale was originally designed
to be the best predictor of the ear’s sensitivity
to tones at high noise levels. Why, then, are
noise measurements for hearing conservation
almost always measured in dBA? Because the
ear’s loudness sensitivity for tones is not the
same as the ears’ damage risk for noise. Even
though the low frequencies and high frequencies
are perceived as being equally loud at high
sound levels, much of the low frequency noise
is actually being filtered out by the ear, making
it less likely to cause damage. The A-weighting
scale in a sound level meter replicates this
filtering process of the human ear."
"Several of hearing conservation’s key documents (including OSHA’s Hearing Conservation Amendment, and EPA’s
labeling requirements for hearing protectors) rely on dBC in determining noise exposures. Today, however, nearly
all noise measurements for hearing conservation are measured in dBA, resulting in misapplications and errors when
figuring attenuation from hearing protectors."