Larson Davis 831, User Manual

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Model 831 Manual Basic Integrated Level Calculations C-5
Dose and Projected Dose Calculations
Dose is a measure of Sound Exposure and is defined in
ANSI S1.25 Section 4.7 as:
See FIGURE C-3 “DOSE and Pro-
jected DOSE" where:
D(Q) is the percentage criterion exposure for exchange rate
Q
T
c
is the criterion sound duration = 8 hours
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
L , or equals -× when the A-weighted sound level is
less than Lt
L
t
is the threshold sound level specified by the manufacturer
L
C
is the criterion sound level specified by the manufacturer
Q is the exchange rate in dB, and q = the parameter that
determines the exchange rate, where:
q = 10 for a 3dB exchange rate
q = 13.29 = 4/log(2) for a 4 dB exchange rate
q = 16.61 = 5/log(2) for a 5 dB exchange rate
q = 20 = 6/log(2) for a 6dB exchange rate
The factor of 100 in the equation produces a result that is a
percentage.
Dose is obtained from the accumulations made for TWA and
SEL using the formula:
where,
D Q
 
100
T
c
---------
 
 
10
L L
c
–
q
--------------
 
 
dt
0
T


=