3M eg4 Marine Instruments User Manual


 
Views on the Edge
Definitions of data log values and views
053-644, Rev E Page 19 eg4 & eg3
19
To set up the Edge and work with noise-level data, you will want to have a good
understanding of the terms listed in Table 3-1.
NOTE: The following table is based on A-weighted, slow measurements. Thus, if you
choose A or C-weighted with Fast or Slow response the measurement values will change
on the display (i.e., you selected sound pressure level with C-weighting with Fast response,
it will display as LCF.) For further details, please see Dosimeter measurement
descriptors/variants in Table 3-2.
Views on the
EDGE
Explanation
L
AS
Sound pressure level - is the basic measure of noise loudness,
expressed in decibels. (In DMS this is noted as “SPL”)
L
ASMX
Maximum sound level- is the highest sound level recorded during a
measurement interval with a particular response setting (Slow or Fast) and
weighting (A or C). LMax is the highest value that is included in LAvg or
dose calculations.
Under OSHA regulations, unprotected workers may not be exposed to
maximum sound levels greater than 115 dB, measured with a Slow
response rate.
L
CPK
Peak Level - is the highest instantaneous sound pressure level recorded
during a measurement interval. Unlike the maximum level, the peak is
detected independently of dosimeter settings for response rate or
weighting.
Under OSHA regulations, unprotected workers may not be exposed to
peak sound levels greater than 140 dB.
L
ASMN
Minimum sound level - The lowest sampled sound level during the
measurement interval allowing for the unit’s Response Time setting (Fast
or Slow).
L
AVG
Average sound level - (in dB) computed for a chosen time duration,
based on a 4, 5, or 6 dB exchange rate. L
AVG
with a 3 dB exchange rate is
referred to as LEQ (equivalent sound level). All sound levels at or above
the threshold level are averaged into the calculations relating to noise
exposure. L
AVG
is typically calculated with no threshold, with a threshold of
80 dB or with a threshold of 90 dB.
Table 3-1: Dosimeter views and definitions