Casella CEL CEL-310 - Manual (Page 43)

Appendix 1
Assuming the noise level for the rest of the
8 hour reference period is “quiet”, the L
EP,d
will be:
Lower than the L eq when the
measurement duration is less than
8 hours,
Equal to the L
eq for a measurement
of 8 hours,
Higher than the L
eq for measurements
longer than 8 hours.
For example, if a noise measurement
was made for 4 hours and the L Aeq value
was 90 dB(A), the L EP,d value would be
calculated to be 87 dB(A) as the measure-
ment duration is half the 8 hour Criterion
Time and the exchange rate is 3 dB.
L eq
The equivalent continuous sound pressure
level, i.e. the average sound pressure level
in dB.
Overload
Indicated when the input to a sound level
instrument is too high for the current
measurement range.
Peak
The maximum level in dB reached by the
sound pressure at any instant during a
measurement period.
With the Dose Badge system, Peak is
measured with C-weighting.
It is the true peak level of the pressure
wave, which should not be confused with
the highest sound pressure level, termed
L
max .
In the Dose Badge system the peak
level is measured, and a record kept of
whether the preset 140 dB(C) Peak
Threshold has been exceeded. When this
level has been exceeded, the downloaded
peak data will be flagged Exceeded,
otherwise it will be flagged OK.
The 140 dB(C) Peak level is a factory
setting that can not be changed by the
user. However, a different peak threshold
can be specified at the time of ordering, or
the threshold can be changed by Casella
CEL or an approved service centre.
Personal Sound Exposure Meter
An instrument for measuring the noise
exposure of a person.
SEL
The sound exposure level that would
contain the same amount of energy in one
second as contained by the actual noise
during the whole measurement period.
When measured with A-weighting, it is
usually identified as L
AE .
The term SEL is not used in OSHA
measurements.
Slow Time Weighting
A standard time weighting applied by the
noise measurement instrument.
Sound Level
The sound pressure level. It is usually
measured with a frequency weighting such
as A- or C-weighting.
SPL
The sound pressure level. This is the basic
physical measure of noise, and is normally
expressed in dB.
Threshold
A threshold below which sound levels are
excluded from calculation. OSHA
measurements use an 80 dB threshold and
call for a hearing conservation program to
be implemented when the eight hour TWA
exceeds 85 dB (50% dose).
In the Dose Badge system, a Peak
Threshold is also applied, above which an
Exceedance is recorded. See Peak.
Time History
In the Dose Badge system a sample of the
noise levels is taken every second
throughout the measurement period to give
a noise profile.
CEL-310 Dose Badge Users Handbook - Page 43