CASELLA CEL CEL-62 Series, Руководство оператора

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8. APPENDIX A
GLOSSARY OF TERMS
This Appendix gives a glossary of the acoustic terminology used in this manual. For
further information, please contact Casella CEL or your local representative.
A, C and Z WEIGHTING (WEIGHTED)
A standard weighting of the audible frequencies designed to approximate the response
of the human ear to noise.
ACOUSTIC CALIBRATOR
An instrument that provides a reference noise source with a standard level and
frequency used to calibrate and check the performance of sound level meters and noise
dosimeters.
Decibel (dB)
The standard physical unit for measuring sound level and noise exposure.
dB(A)
A-weighted sound level in decibels.
dB(C)
C-weighted sound level in decibels.
dB(Z)
Z-weighted sound level in decibels.
FAST TIME WEIGHTING
A standard time weighting applied by the sound level measurement instrument.
L
AE
The A-weighted exposure level is the level that would contain the same amount of
energy in one second as the actual noise has during the whole measurement period.
L
Aeq
The A-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. For example, if the noise
level in a factory was a constant 85dB and the measurement period was 4 hours, the
LAeq would be 85dB(A). The calculation of LAeq does not use a threshold as in the
calculation of LAVG, except for the LAEQ (T80) parameter defined for the ACGIH
standard.
L
AF
The A-weighted sound level measured with Fast time weighting.
L
AS
The A-weighted sound level measured with Slow time weighting.
L
ASmax
The maximum A-weighted sound level measured with Slow time weighting.
L
AVG
This is a parameter used in OSHA measurements. It is the average sound level over the
measurement period (equivalent to Leq). Normally the term is used when the exchange
rate Q is some value other than 3, such as for measurements used for the OSHA
Hearing Conservation Amendment with Q=5. A Threshold value is used during the
calculation of LAVG, where any levels below the threshold are not included. For
example, assume the threshold level is set to 80dB and the exchange rate is 5dB (Q =
5). If a one hour measurement was taken in an environment where the noise levels vary
between 50 and 70dB, the sound level would never exceed the Threshold so the
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