EN-22
The time weighting network of the sound level meter performs index averaging on the
square of the sound pressure signal. The equivalent circuit is shown at right.
ττττ
is the
time constant, which equals CR.
The response of the index averaging circuit to a single burst signal is shown below.
C
R
：Input voltage
= C R
：Output voltage
Equivalent electrical circuit
e
i
e
i
e
o
e
o
e
i
:
Input voltage (proportional to
square of sound pressure)
e
o
: Output voltage
e
: Logarithm base
ττττ
: Time constant
t
: Time
e
i
e
e
i
1
( 1- )
t
t
S
i
g
n
a
l
a
m
p
l
i
t
u
d
e
r
m
s
a
m
p
l
i
t
u
d
e
e
o
Burst signal response
