| Dynamic
range
Dosemeters
typically have a
dynamic range of 50
–60 dB.
A
noise does of 4 hours
at 90 dBL Aeq
is equivalent to one
of 80 dBL Aeq
for 40 hours.
On the other
hand, the same dose is
achieved after only 24
minutes exposure to a
noise level of 100
dB(A).
Relatively
quiet sounds have a
negligible effect on
the overall noise dose
and there comes a
point when it is not
worth measuring them.
This lower
limit is generally
fixed at 5 dB below
the acceptable limit
for 8 hours’
continuous exposure.
Conversely,
loud sounds, even if
they last only a few
minutes, can have a
considerable effect on
the total noise dose. It
is important that a
meter should be able
to detect the louder
noises without
clipping the peaks, or
it could give an
underestimate of the
noise dose it is
trying to measure
A
dynamic range of
80-140 dB(A) should
therefore be adequate
to cover most of the
situations a hygienist
is likely to come
across.
As an
additional safeguard,
most dosemeters have
an overload warning
indicator, which is
activated if the
signal has been
clipped at all.
» Basic
Construction
» Principles
of Operation
» Dynamic
Range
» Calibration
» Use
of Dosemeter in the
Field
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