Page 93
Function
Equation
Daily Personal
Noise Exposure
Level
L
epd
10 log
⋅
1
T
n
T1
T2
t
P
2
t
( )
P
o
( )
2
⌠
⌡
d
⋅
dB
⋅
:=
L
epd
L
AeqT
10 log
⋅
T
2
T
1
−
(
)
T
1
⋅
dB
+
:=
L
epd
L
AeqT
10 log
⋅
ExposureTime
8
dB
⋅
+
:=
P(t) is the instantaneous A-weighted sound pressure in
Pascal’s
P
o
is the reference sound pressure of 20µPa
T
n
is the normalization period governed by the Criterion
duration (8 hours typical)
L
AeqT
is the equivalent continuous A-weighted time-average
sound level (re 20 µPa) in dB
Exposure Time or ET is set on the instrument in hours and
is the period in which the recipient is exposed or subject to
the noise source
Noise Dose
Using
Measurement
Time
Dose
100
T
C
0
T
t
10
L LC
−
(
)
Q
log2
⌠
⌡
d
⋅
:=
Dose
MT
(
)
100 T
⋅
T
C
10
L LC
−
(
)
Q
log2
⋅
:=
T
C
is the Criterion duration in hours (8 hours typical)
L is the Slow (or Fast) frequency (A) weighted sound level
L
C
is the Criterion level in dB
T is the Log Length (Measurement period) in hours
Q is the Exchange Rate constant
