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Noise Dose
This is the amount of noise a person is subject to over a work shift and is
expressed as a percentage.
The noise dose is calculated using the criterion level (LC), criterion duration (TC)
which is 8 hours, exchange rate (Q) and the total measurement time (T).
Dose
100 T
⋅
T
C
10
L LC
−
(
)
Q
log2
⋅
:=
In the UK the criterion level is 85dBA and therefore: -
100% dose = 85dBA for an 8 Hour Shift
Each time the sound level increases by 3dB the dose doubles given the same
measurement time, similarly if the sound level decreases by 3dB the dose will
halve for the same measurement time. See the following table: -
Lp
dBA
Measurement Time
(Hours)
Dose
%
94
8
800
91
8
400
88
8
200
85
8
100
82
8
50
79
8
25
Doubling the measurement time doubles the dose and halving the measurement
time halves the dose given the same sound level. See the table below: -
Lp
dBA
Measurement Time
(Hours)
Dose
%
85
32
400
85
16
200
85
8
100
85
4
50
85
2
25
85
1
12.5
See also ‘Criterion Level (LC)’, Criterion Duration (TC)’, ‘Exchange Rate’ and
‘Function Equations’ for a mathematical description of noise dose.
