Larson Davis SoundAdvisor 831C Reference Manual page 216

Sound Power (W)
SoundAdvisor Model 831C
Instantaneous: The time varying reading on a meter face on in a meter output
due to changes in the sound pressure. The reading will depend on the time-
weighting applied.
The fundamental relationship between the two is logarithmic
L
where p is the reference sound pressure of 20 µPa. The square of the sound
0
pressure is a power-like quantity that can be expressed in the original form of the
level definition
L p
Sound Pressure Level can be converted to sound pressure as follows. If the sound
pressure is 1 Pascal, then the sound pressure level is
L = 20log
p 10
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

Pa = 20 10
Energy Average (L
eq
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" on page C-13..
Impulse: The value of an impulsive sound. The reading will depend on the time-
weighting applied.
Unweighted Peak: The peak value of a sound with a meter that has flat
frequency weighting and a peak detector.
Weighted Peak: The peak value of a sound with a meter that has a frequency
weighting other than flat and a peak detector.
The sound power emitted by a sound source. It is measured in Watts.
p rms
------------
= 20log
p 10
p
0
2
p
rms
------------
= 10log 10
2
p
0
1

--------------------- -
= 20log
10
6 –

20 10

6 – 76.3 20 3.815 6
 
10 = 20 10
): The value of a steady sound measured over a fixed time

L p 20
p = p 10
rms 0

L p 10
2 2
p rms = p 0 10
  
50000 = 20 4.699 =
– – 2.185
 
= 20 10 = 20 0.0065
94.0dB

= 0.13
C-14