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400
Series
EN - 53
7.1.1. dB
mode
3. Connect the sound level probe to the instrument’s optical input by means of the optical cable
4.
Press the
GO/STOP
key. The instrument starts
measuring the acoustic pressure. The following
values are displayed:
SPL
acoustic
pressure
Peak
acoustic pressure peak
Duration time elapsed since the
beginning of the recording
A U X
S P L - - - -
d B
P e a k - - - - d B
D u r a t i o n 0 0 0 0 : 0 0 : 0 0
dB
Func
5.
Press the
GO/STOP
key again. The instrument
stops measuring and displays the following
values:
Leq
equivalent level of acoustic
pressure
Peak
acoustic pressure peak
Duration duration of the recording
A U X
L e q - - - -
d B
P e a k - - - - d B
D u r a t i o n 0 0 0 0 : 0 0 : 0 0
dB
Func
The equivalent level of the acoustic pressure is defined as:
2
0
0
2
10
1
log
10
P
dt
P
T
Leq
T
i
where: P
0
is the reference pressure, ca. 2
10
5
Pa
P
i
is the instant pressure of the acoustic range
In praxis, the following formula is used:
N
N
Leq
N
i
L
i
i
1
10
10
10
log
10
where: L
i
is the sampled level [dB]
N
i
is the number of samples measured for the L
i
level
N is the number of samples measured
6.
7. Please note that Lep, the personal exposure level, is defined as the equivalent level of
the acoustic range a person is exposed to during a normal workshift (8 hours). "Lep"
coincides therefore with "Leq" calculated for 8 hours.
8.
Once recording is completed, measures can be saved by pressing the
SAVE
key twice or the
SAVE
key and, subsequently, the
ENTER
key (§ 9.1)