730/730-IS Dosimeter Manual
B-8
Projected Sound Exposure (E
8
or E
40
)
Projected Sound Exposure shows what the actual sound exposure will be for a specific time period if the current
Equivalent-Continuous Sound Level (L
eq
) remains at its current level. The dosimeters calculate an 8-hour and a 40-
hour projected sound exposure.
AND
Projected Time-Weighted Average, P.TWA(x)
The projected Time-Weighted Average is the Equivalent Time Weighted Average assuming that the current rate of
noise exposure continues for the duration of a work shift (Shift Time). This metric displays as “P. TWA” on the
dosimeter display.
Shift Time
Shift Time is the length of time in hours that a dosimeter subject could be exposed to noise at work. It’s used to
calculate Projected LEP, d; P. LEX, 8h; Projected Dose; and Projected TWA. In the dosimeter Settings, enter the Shift
Time at the following locations:
Settings
Dosimeter 1, 2
, or
3
.
Single Event Noise Exposure Level (SENEL, L
AX
)
The Single Event Noise Exposure Level is the total sound energy over a specific period. It is a special form of the
Sound Exposure Level where the time period is defined as the start and end times of a noise event such as the
passing of an aircraft or automobile.
Sound Exposure (E)
The total sound energy of the actual sound in a given time interval. For a dosimeter, the time interval is the record’s
Run Time. The units for sound exposure are Pa
2
S (pascal squared seconds) or Pa
2
H (pascal squared hours).
p
(t) = instantaneous, frequency weighted (A, C, or Z), sound pressure in pascals
T
2
– T
1
= measurement period or Run Time
L
avg
= average sound level in dB, only recording
values higher than the user specified threshold
level
T
S
= work shift duration or Shift Time
T
C
= Criterion Duration in hours (8 hours)
q = exchange rate constant
• If exchange rate = 3, q = 10
• If exchange rate = 4, q = 4 / log
10
(2) ≈ 13.29
• If exchange rate = 5, q = 5 / log
10
(2) ≈ 16.61
• If exchange rate = 6, q = 20
p
(t) = instantaneous, frequency weighted (A or C), sound pressure in pascals
T
2
– T
1
= measurement period or Run Time
