Larson Davis 831, Руководство пользователя

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Model 831 Manual Glossary D-19
The fundamental relationship between the two is logarithmic
where p
0
is the reference sound pressure of 20 µPa. The
square of the sound pressure is a power-like quantity that
can be expressed in the original form of the level definition
Sound Pressure Level can be converted to sound pressure as
follows. If the sound pressure is 1 Pascal, then the sound
pressure level is
Calibrators often use a level of 94 dB so they generate a
sound pressure of 1 Pascal.
If the sound pressure level = 76.3 dB, then the sound
pressure is
Energy Average (L
eq
) : The value of a steady sound measured
over a fixed time period that has the same sound energy as
the actual time varying sound over the same period. This
descriptor is widely used. It is a fixed average (See Sound
Pressure).
Impulse : The value of an impulsive sound. The reading will
depend on the time-weighting applied.
L
p
20log
10
p
rms
p
0
----------
= p
rms
p
0
10
L
p
20

=
L
p
10log
10
p
rms
2
p
0
2
----------
= p
rms
2
p
0
2
10
L
p
10

=
L
p
20log
10
1
20 10
6 – 
----------------------
20log
10
50000
 
20 4.699
 
94.0 dB = = = =
Pa 20 10
6 –

10
76.3 20


20 10
3.815 6 –

20 10
2.185 –

20 0.0065
 
0.13 = = = = =