Casella CEL CEL-35X dBadge - Manual (Page 40)

Casella CEL-35X dBadge Users Handbook – Page 40
*with Q5, threshold 70-90 (default 80dB) and criterion 70-90 (default
90dB) in 1dB steps.
#
Threshold T80
…T90… or T80+T90.
1
displayed on the CEL-35X, remainder shown on Casella insight data
management software
2
displayed on CEL-352 dB
adge „Plus‟ model only
The dBadge also stores 1-minute values of the following parameters
(Except dBadge
„Lite‟):
L
Aeq
, L
Aavg
, L
Cpeak
, L
Zpeak
.
10.3 Using the CEL-352 for the Selection of
Hearing Protection
The CEL-352 dB
adge „Plus‟ can be used for the selection of hearing
protection by 2 different methods. These are the Single Number
Rating (SNR) and the High, Medium, Low (HML) methods. Hearing
protection manufacturers will provide data as follows:
HML values H=31 M=25 L=17
SNR value = 28
The SNR value is a single value which represents the attenuation of
the hearing protection. The Sound Pressure Level (SPL) at the ear
can be calculated as follows:
A-weighted SPL at the ear = L
Ceq
– SNR
For example, if the measured L
Ceq
from the CEL-352 dB
adge „Plus‟
was 102dB, and using the value for SNR in the example above
A-weighted SPL at the ear = 102
– 28 = 74dB(A)
The HML method is a more effective method of calculating the
effectiveness of hearing protection because it takes into account the
frequency component of the noise. This is because the H, M and L
values is the attenuation of the hearing protection at high, medium
and low frequencies respectively.