Sound sources higher to this level are recorded without distortion if and only if the maximum peak level does not exceed: 105+30 =
135dB peak.
Generally, sound sources have some high peak factors, pretty much from 20 to 30dB. That's why it is not
possible to set the gain at a value lower than 24dB. However, in situations where sound sources are
elaborated with very high peak factors, it is possible to choose the digital gain beyond 30 dB between:
36-42-
48 dB
During programming,
DB300
instrument displays maximum and minimum peak pressure levels properly
recordable according to the selected criterion (reference threshold and digital gain).
Listening comfort
:
It is recommended to keep the factory setting which is 30 dB. Eventually, after experience on site, it is possible
to bring it to 24 dB.
In this case, the re-listening allows a correct identification for the 4 seconds before and after the adjustable threshold exceeding.
Note
: to make more comfortable the re-listening on PC, we advise the use of an external amplified speaker system to the PC.
12.3Use of audio recording
From
MENU
screen, select
“PROG.MESURE”
➢
Press
OK
to validate.
➢
Move the cursor on
“Audio”
.
➢
Select
YES
in reverse video.
➢
Move the cursor to select successively:
•
The used reference for the detection:
LAeq
or
Lpk
.
•
The threshold beyond which the recording starts. This threshold can be set with the scrolling knob key
in step of 1 dB and concerns either the
LAeq
or the
Lpk
according to the previous selection.
•
The gain of the recording chain adjustable from
24 dB
to
48 dB
in step of
6 dB.
According to this
selection, maximum and minimum recordable values of peak pressure levels correctly calculated are
displayed.
Note
: Durations
of pre and post recordings supervising the exceeding are not adjustable and fixed at 4
seconds.
Measurement in progress:
Different recordings are performed automatically without intervention and without affect metrological calculations. Total recording time
available being limited
(see page 65), be selective to select the detection threshold value in order to not use too quickly memory space
and get repetitive and insignificant recordings.
Audio files:
All recordings are linked to the corresponding metrological file and saved as
*.wav
audio format on the micro SD card. During data
transfer on a PC, the
software (LDS300 or LDB300) processes all the files and the re-listening of files to help about sound sources
recognition.
Listening of the audio files without software:
Audio files can be processed by a software (LDS300 or LDB300). However, if you don't have software, it is possible to listen to the
*.wav
files with any kind of software suitable with *.wav and PC . It is possible to listen to the recording but it is not possible to link them
with metrological data.
Audio files are on the same directory and its name is the name of the metrological data file.
50
Audio recording function
Filt.10Hz
Lpk
Audio
Ref
Seuil dB
Gain dB
Max dB
min dB
PROG. MESURE
oui
LAeq
85
30
109.0
59.0
non
C
: :
CONFIGURATION
CONFIGURATION
I/O
LECTURE
PC
PROG. MESURE
INSTRUMENT
A PROPOS
AUTONOMIE
COMMENTAIRE
Filt.10Hz
Lpk
Audio
Ref
Seuil dB
Gain dB
Max dB
min dB
PROG. MESURE
oui
LAeq
85
30
109.0
59.0
non
C
Filt.10Hz
Lpk
Audio
Ref
Seuil dB
Gain dB
Max dB
min dB
PROG. MESURE
oui
LAeq
85
30
109.0
59.0
non
C
Metrological data file
Directory of *.wav files
Detail of *wav files
