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Frequency
Frequency Weighting Curves
Figure 1 – Frequency Weighting Curves
Frequency Weighting Filters
Frequency Weightings are where the Sound Pressure Level (SPL) is modified by
use of filtering. All Sonus Pocket Meters use electronic frequency weighting
filters between the standardised frequencies of 10Hz and 20,000Hz.
Depending on your instrument type (see
Technical Specifications
for further
details), the following standardised frequency weightings are available: -
‘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 200Hz and
1250Hz and has -3dB points at 31.5Hz and 8kHz. It is generally used for the
acoustic emissions of machinery and for peak sound levels.
‘Z’ Weighting (Zero) – (Models ‘E’ & ‘L’ Only)
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
