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3.5 Filter Setting (HL 5000 Professional)
3.5.1 What are filters?
One of the characteristics of a sound is its frequency. Technically
speaking, the frequency of a sound is the number of waves generated
by that sound per cycle. The greater the number of waves per cycle,
the higher the frequency of the sound. In turn, the higher the
frequency a sound has, the higher in pitch that sound will be. Low-
frequency sounds are low-pitched; high-frequency sounds are high-
pitched. Leaks on plastic and PVC lines typically create low-
frequency sounds and are low-pitched to the ear; leaks on copper and
other metallic lines tend to create high-frequency sounds and are
high-pitched to the ear
.
The HL 5000
is designed to measure and display sound levels at
frequencies from 0 to 4,000 Hz. On the Filter Menu screen, this broad
spectrum is divided into 9 smaller frequency bands arranged in
ascending order (0 - 70, 106, 160, 240, 360, 540, 800, 1200, 1800 -
4000 Hz) and each of these
smaller frequency bands is called a filter.
Any sound that the HL 5000
hears and analyzes is broken down
into the individual frequencies that created the sound, and the process
of selecting specific frequency bands, or filters, for the HL 5000
to
focus on - or to ignore - is referred to as setting the filters.
3.5.2 Filter Selection
While the unit is in listening or measurement mode, go to the filter
selection screen. This is done by pressing the soft key
under the Filter Menu icon found on the Main Screen.
The 9 vertical bars displayed on the Filter Selection screen (one for
each corresponding filter) show the user how much (or how little) each
individual frequency is contributing toward the overall sound(s) being
processed by the HL 5000
at that moment. The presence or
absence of activity on any particular frequency, or filter, can help the
user decide whether or not to select it for measurement. When a
filter, or group of filters is selected for measurement, three things
happen:
