Larson Davis SoundTrack LxT, Руководство пользователя

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LxT Manual Glossary and Formulas
C
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19
Noise
Typically is unwanted sound. This word adds the response of
humans to the physical phenomenon of sound. The
descriptor should be used only when negative effects on
people are known to occur.
Ambient: The all encompassing sound at a given location
caused by all sources of sound. It is generally random, but
need not be.
Background: The all encompassing sound at a given location
caused by all sources of sound, but excluding the source to
be measured.
Pink: A random sound that maintains constant energy per
octave. Pink light is similar to pink noise in that it has a
higher level at the lower frequencies (red end of the
spectrum).
White: A random sound that contains equal energy at each
frequency. In this respect, it is similar to white light.
Noise Dose (D)
Dose is a measure of Sound Exposure and is defined in
ANSI S1.25 Section 4.7 as:
See FIGURE C-1 “DOSE and Pro-
jected DOSE" where:
D(Q) is the percentage criterion exposure for exchange rate
Q
T
c
is the criterion sound duration.
T is the measurement duration in hours.
t is the time in hours.
L is the SLOW, (or FAST) A-weighted sound level, a
function of time, when the sound level is greater than or
equal to
Lt , or equals - ∞ when the A-weighted sound level is
less than Lt.
D Q
 
100
T
c
---------
 
 
10
L L
c
–
q
--------------
 
 
dt
0
T


=