Larson Davis 824 User Manual

9/29/09 D-21
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.
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.
Sound Power(W) The sound power emitted by a sound source. It is measured
in Watts.
Sound Power Level (PWL, L
w
) The logarithmic form of sound power. It is also expressed by
attachment of the word decibel to the number. The logarithm
is taken of the ratio of the actual sound power to a reference
sound power, which is 1 pico-watt. Sound power level
cannot be measured directly, but can only be deduced
L
p
20log
10
1
20 10
6–

----------------------
20log
10
5000020 4.69994.0dB====
Pa 20 10
6–
 10
76.3 20
 20 10
3.815 6–
 20 10
2.185–
 20 0.00650.13=====

Larson Davis 824 Specifications

General

Brand	Larson Davis
Model	824
Category	Measuring Instruments
Language	English