Instruction Manual
Sound Level Meter Types 2245 –
Instruction Manual
Page 32 of 110
Taktmaximal-Mittelungspegel
The Taktmaximal-Mittelungspegel,
L
AFTeq
(T)
, is defined as ten times the logarithm to
base ten of the mean of ten to the power of the Taktmaximalpegel,
L
AFT
(Tn)
, divided by
ten during a time interval. The time interval is starting at
t
=
T
and ending at
t
=
T
+
N
·Δ
t
where:
T
is the start time of the measurement, indicated as
Start Time
Δ
t
is the Taktzeit, equal to 5 seconds
N ·
Δ
t
is the averaging time interval, indicated as
Elapsed Time
The Taktmaximal-Mittelungspegel is expressed in decibels (dB). In symbols,
Taktmaximal-Mittelungspegel,
L
AFTeq
(T)
, is given by:
The symbol used by the sound level meter for Taktmaximal-Mittelungspegel is:
L
AFTeq
Sound Exposure Level
The sound exposure level,
L
xE
(T)
, is defined as ten times the logarithm to base ten of
the ratio of integral of the squared sound pressure during a time interval to the
reference sound exposure, sound pressure being obtained with a frequency weighting,
x
. The time interval is starting at
t
=
T
and ending at
t
=
T
+ Δ
t
where:
x
is A for A-weighted, B for B-weighted, C for C-weighted or Z for Z-weighted
T
is the start time of the measurement, indicated as
Start Time
Δ
t
is the averaging time interval, indicated as
Elapsed Time
The equivalent continuous sound level is expressed in decibels (dB). In symbols,
equivalent continuous sound level, L
xE
(T), is given by:
where:
ξ is a dummy variable of time integration over the averaging time interval
p
x
(ξ) is the x frequency-weighted instantaneous sound pressure
E
0
is the reference sound exposure, equal to (20 μPa)
2
×(1 s) = 400×10
–12
Pa
2
s
The sound exposure level L
xE
(T) can also be expressed in terms of the equivalent
continuous sound level L
xeq
(T) and
Elapsed Time
as:
where Δ
t
is the averaging time interval, indicated as
Elapsed Time
, expressed in seconds.
The symbols used by the sound level meter for sound exposure levels are (for A, B, C
and Z frequency weighting):
L
AE
,
L
BE
,
L
CE
,
L
ZE