9320 Reference Controller Operating Manual 39 (52)
9320 Reference Controller can follow the accumulation of the noise dose due to listening to audio and
enables the accumulated dose to be monitored. The standard for accumulating the dose is selected in
the 9320 setup using the GLM software. The dose is naturally a personal quantity, so if the same 9320
dose is valid for one person working in the monitoring space. If several persons take turns to use the
space, single dose calculation in 9320 is not accurate for an individual.
In terms of selecting the noise dose standard to use, the highest protection for hearing is obtained using
the standard setting the criterion level and the rate to the lowest values. In this regard, the use of the
ITU-T recommendation H.870 mode 1 or mode 2 settings are cosidered a safe choise. It is always
advisable to use low monitoring level for long duration monitoring and only increase the monitoring level
for short periods of time when needed for maximum audibility.
Table 4. Noise dose calculation standards available in 9320A
Parameter
-OSHA (EU)
(US)
(US)
(US)
(US)
Explanation
L
crit
80 75 85 90 85 85 85
Criterion level, unit dB SPL
The sound level accumulating 100% dose during a
criterion duration of T
crit
hours.
T
crit
8 8 8 8 8 8 8
Criterion duration, unit hours
This is the assumption of the duration of a standard
working day.
rate 3 3 3 5 3 3 4
Exchange rate, unit dB
Dose accumulation speed is doubled when the sound
level increases by ‘rate’ dB.
L 77 72 80 80 80 80 80
Threshold (or cutoff) level
The sound level considered safe. No dose is cumulated
when the SPL is below L.
Some standards related to occupational noise exposure include the following
ITU-T Recommendation H.870 (International)
ISO9612, ISO1999 (International)
EU Directive 2002/49/EC (Europe)
OHSA 1910.95 (USA)
Some standards related to the accuracy needed for measuring personal exposure include
IEC 61252 (Personal sound exposure meters, international)
1
1
The personal sound level meter accuracy grade corresponds to that for an integrating sound level
meter which complies with the Type 2 requirements of IEC 60804 for an A-weighted sound pressure
level range from 80 dB to 130 dB and a nominal frequency range from 63 Hz to 8 kHz.
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