Spartan 821/721 Manual
Glossary
C-8
Frequency Weightings
Frequency weightings are commonly-used frequency filters that adjust the amplitude of
all parts of the frequency spectrum of the sound of vibration.
• A-Weighting: A weighting filter that most closely matches how humans perceive
sound, especially low to moderate levels. This weighting is most often used for
evaluation of environmental sounds. Notated by the “A” in measurement
parameters, including dBA, L
Aeq
, L
AF
, L
AS
, etc.
• C-Weighting: Commonly-used filter that adjusts the levels of a frequency spectrum
in the same way the human ear does when exposed to high or impulse levels of
sound. This weighting is most often used for evaluating equipment noise.
• Flat or Linear Weighting: No longer used in current standards. Flat weighting indi
-
cates that no filter was applied across a stated frequency range. Since 2003, the
IEC 61672 standard notes the use of Z-weighting, instead.
• Z-Weighting: “Zero” or no frequency weighting applied. I actuality, a passband fil
-
ter from 10 Hz to 20 kHz. noted by the “Z” in measurement metrics, including
dBZ, L
Zeq
, L
ZF
, L
ZS
, etc.
L
EP
, d
The acronym used on the meter interface for the level of daily personal noise exposure.
For more information, see the entry for
Daily Personal Noise Exposure (LEP,d)
.
L
eq
Equivalent Continuous Sound Level (L
, and
Level (dB)
A descriptor of a measured physical quantity, typically used in sound and vibration
measurements. It is attached to the name of the physical quantity to denote that it is a
logarithmic measure of the quantity and not the quantity itself. The word decibel is
often added after the number to express the same thing. When frequency weighting is
used the annotation is often expressed as dB(A) or dB(C).
L
max
The maximum value, expressed in dB, of the Frequency and Exponential-Time Weighted
Sound Level (
L
ωτ
) in a given time interval. For the dosimeters, an L
max
value is recorded
for 2 different time intervals. The first records L
max
for the entire record’s time. The
second records L
max
for each individual time history sample.
‐50
‐40
‐30
‐20
‐10
0
10
20
200
2000
20000
C Weighting
A Weighting
Z Weighting
