Casella CEL CEL-281 - Manual (Page 29)

2.2.5 Noise Dose
Noise dose is not an absolute measurement but a percentage of the rec-
ommended maximum daily personal noise exposure.
In this way, 100% noise dose will be equal to the exposure limit for the
person, while values lower than 100% indicate a lesser exposure than
the allowable dose and values above 100% show excessive exposure.
The Daily Sound Exposure (E A,d ) is the total A-weighted sound expo-
sure sustained in a "typical working day", while the , aily Sound Expo-
sure Level (L EP,d ) is the E A,d expressed as an equivalent continuous
sound level (L Aeq ) over a normalised working day of eight hours.
Note: These expressions all use an exchange rate Q = 3, and the following equations
will not be valid for other values of Q.
The formula for equivalent continuous sound level L Aeq is:
L Aeq = 10 log 10
1
T ∫ (
0
T
P A
P 0
) 2
dt
Which for a normalised 8 hour day becomes:
L EP,d = 10 log 10
1
T 0
E A,d
(P 0 ) 2
Where:
T 0 = 8 hours,
P 0 = 2 x 10
-5
Pa
Therefore the formula can be re-written as:
L EP,d = 10 log 10 E A,d + 85 (dB)
CEL-281 Operator's Handbook - Page 21
_Introduction