Environmental Engineering Reference
In-Depth Information
Figure 8: Sound pressure levels examples [ 9 ].
broadband sound level. For the determination of the human ear's response to changes
in sound, sound level meters are generally equipped with fi lters that give less weight
to the lower frequencies. There are a number of fi lters that accomplish this:
A-weighting: This is the most common scale for assessing environmental and
occupational noise. It approximates the response of the human ear to sounds of
medium intensity.
B-weighting: This weighting is not commonly used. It approximates the ear for
medium-loud sounds, around 70 dB.
C-weighting: Approximates response of human ear to loud sounds. It can be
used for low frequency sound.
G-weighting: Designed for infrasound .
Details of these scales are discussed by Beranek and Ver [7].
Once the A-weighted sound pressure is measured over a period of time, it is
possible to determine a number of statistical descriptions of time-varying sound
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