D-20 Glossary Model 831 Manual
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
through measurements of sound intensity or sound pressure
around the source. The equation for it is
Sound Speed The speed at which sound waves propagate. It is measured
in meters per second. It should not be confused with sound
or particle velocity which relates to the physical motion of
the medium itself.
Spectrum (Frequency
Spectrum)
The amplitude of sound or vibration at various frequencies.
It is given by a set of numbers that describe the amplitude at
each frequency or band of frequencies. It is often prefixed
with a descriptor that identifies it such as sound pressure
spectrum. It is generally expressed as a spectrum level.
L
w
10log
10
W
W
0
-------
= WW
0
10
L
w
10
=
To Next Page
Loading...
