12 Audio recording function
When studying a measurement and after the visualization of the temporal evolution with the software, some results can be surprising
and can raise questions:
What is the sound source of the this level?
In order to help you,
DB300
instrument has an
“Audio Recording”
function that is automatically activated when a previously set
threshold is exceeded.
This detection on threshold is about:
•
The equivalent continuous level A-weighted on an elementary integration time of 1 second:
LAeq,1s
or
•
The maximum peak pressure level C or Z-weighted (according to the programmed weighting: usually C):
LCpk
This function is only available with the two following modes:
Integrating-averaging sound level meter with storage – A and C weightings
Integrating-averaging sound level meter with storage – A, C and Z weightings and analyzer by filters of octave
bands from 16 Hz to 16 kHz (class 1) or from 31.5 Hz to 8kHz (class 2)
Integrating-averaging sound level meter with storage – A, C and Z weightings and analyzer by filters of octave
bands of third octave bands from 12.5 Hz to 20 kHz (class 1) or from 31.5 Hz to 8kHz (class 2)
(option)
The principle of recording after a threshold detection suggests that sound source that caused the threshold exceeding can become
inactive after the detection. Therefore,
DB300
instrument systematically performs a sliding recording of
Tgl
duration (4 s) that is
retained after detection of an exceeding.
The recording keeps going on the total duration of the exceeding and after sub-overshoot of the threshold, and on the same
Tgl
duration previously used.
This process allows an
“Audio recording”
of the sound source that causes the exceeding and makes easier its identification.
As it is a help for the recognition of sound sources and in order to optimize material resources, the audio recording format on the SD
card is defined as follows:
•
Accuracy: 16 bits
•
Sampling: 12 kHz
DB300
instrument having a wide measurement dynamic, 107 dB it is likely that the re-listening with a computer does not allow an easy
identification according to the selected detection threshold.
To optimize the listening, the audio recorder incorporates an adjustable digital gain from 24 to 48 dB with a step of 6 dB. This
adjustment has no incidence on the measurement and interferes on audio files only.
So, according to measurement conditions and selection criteria, this adjustment allows to adjust the reduced dynamic of audio listening
(co ear + environment = about 50 dB) to this more extensive of DB300 instrument (107 dB)
Important:
to make more comfortable the re-listening on PC, we advise the use of an external amplified speaker system to the PC.
48
Audio recording function
