skcinc.com
Form 37177 Rev 200910
Page 7
A Weighting
The SPL is filtered in such a manner as to reflect the hearing response of a human ear. The signal is
progressively attenuated at the higher and lower ends of the audible frequency range but much more
attenuation occurs at the lower end of the audible frequency range. Generally, this is the most commonly
used frequency weighting.
C Weighting
The signal is progressively attenuated at the higher and lower ends of the audible frequency range,
however, the attenuation at the lower end is much less than with A Weighting. The response has a flat
area between 200 and 1250 Hz and has -3 dB points at 31.5 Hz and 8kHz. It is generally used for the
acoustic emissions of machinery and for peak sound levels.
Z Weighting
Often referred to as the FLAT or LIN response, this weighting has a virtually flat response over the entire
audible frequency range.
Z Weighting
A Weighting
C Weighting
-60
-50
-40
-30
-20
-10
0
10
100
1000
10000
100000
dB
Frequency
Frequency Weighting Curves
