Larson Davis Spartan 730, Reference Manual

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730/730-IS Dosimeter Manual B-5
Frequency (Hz, rad/sec)
The rate at which an oscillating signal completes a complete cycle by returning to the original value. It can be
expressed in cycles per second and the value has the unit symbol Hz (Hertz) added, with the letter f used as a
universal descriptor for frequency. It can also be expressed in radians per second (
ω)
, because 2
π
rad/s
corresponds to 1 Hz. The two expressions are related through the expression
ω
=2
π
f.
Frequency and Exponential Time-Weighted Sound Level (
L
ωτ
)
L
ωτ
corresponds to the frequency and exponential-time weighted sound level in dB. It is sometimes referred to as
the “RMS sound level”. Similarly the A, C, or Z frequency weighting is sometimes referred to as the “RMS frequency
weighting,” where RMS is an acronym for root-mean-square.
The Detector rate setting on the dosimeter corresponds to an exponential time constant of SLOW (1 second), which
is designated as
ω
in the equation. These time constants are required by both ANSI and IEC standards.
In the
L
ωτ
equation,
ρ
designates the frequency weighting (A or C). For example, on the dosimeter, L
AS
signifies the
A weighted, SLOW exponential-time weighted sound level. Similarly, L
CF
denotes the C weighted, FAST level.
Frequency Weighting
See also "Frequency and Exponential Time-Weighted Sound Level (L
ωτ
)."
L
EP
, d
The acronym used on the 730 interface for the level of daily personal noise exposure. For more information, see the
entry for “Daily Personal Noise Exposure (LEP,d)” .
L
eq
The abbreviation used on the 730 meter interface for the energy equivalent sound level. For more information, see
the entry for “Energy Equivalent Sound Level (L
eq
)” and “Sound Exposure (E)” .
Level (dB)
Level (dB) is used in G4 LD Utility and in the 730 manual to describe a measured physical quantity, typically used in
sound and vibration measurements. This reference to a physical quantity to denote that it is a logarithmic measure
6.02 20 .50
Exchange Rate,
Q
Exchange Rate
Factor, q
Exposure Factor,
k
(t) = instantaneous, frequency weighted (A or C), sound pressure in pascals
0
= reference sound pressure, 20 µPa
t
= time of observation
ω
= exponential time constant: SLOW (1 s)