Casella CEL
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instrument would record no value for the LAVG. However, if the sound level exceeds the
80dB Threshold for only a few seconds, only these seconds will contribute to the LAVG,
giving a level of around 40dB, which is much lower than the actual ambient sound levels
in the measured environment.
L
Cpeak
The peak C-weighted sound level.
L
EP,d
(L
EX,8h
)
This is the daily personal noise exposure defined by ISO 1999. It is the LAeq normalised
to an 8 hour Criterion Time, i.e. a standard day. Assuming the noise level for the rest of
the 8 hour reference period is “quiet”, the LEP,d will be: lower than the Leq when the
measurement duration is less than 8 hours, equal to the Leq for a measurement of 8
hours, higher than the Leq for measurements longer than 8 hours. For example, if a
noise measurement was made for 4 hours and the LAeq value was 90dB(A), the LEP,d
value would be calculated to be 87dB(A) as the measurement duration is half the 8 hour
Criterion Time and the exchange rate is 3 dB.
L
Ceq
The C-weighted equivalent level is the level that would contain the same amount of
noise energy as in the actual noise, effectively giving an average level over the
measurement period. Following the ISO procedures, doubling the energy results in a
3dB change in the Leq. This is denoted by exchange rate Q=3.
PEAK
The maximum level in dB reached by the sound pressure at any instant during a
measurement period. With the CEL-62X, peak is measured with either C, Z or A
weighting. It is the true peak level of the pressure wave, which should not be confused
with the highest sound pressure level, termed Lmax.
SLOW TIME WEIGHTING
A standard time weighting applied by the noise measurement instrument.
SPL
The sound pressure level. This is the basic physical measure of noise, and is normally
expressed in dB.
THRESHOLD
A threshold level below which sound is excluded from calculation. OSHA measurements
use an 80 dB threshold.
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Summary of Contents for CEL-62 Series
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