BRUEL & KJAER 2225 User Manual

must be made. Readings should be made for the source operating in the presence of
background noise, and for the background noise alone. A correction can then be
made according to the curve of Fig. 3. 4. The difference between the two values is
found, and the correction curve is entered on the horizontal axis at this value. The
corresponding correction value obtained from the vertical axis is then subtracted
from the higher of the two measured values.
5 . To make a new measurement in "60s L eq, "Peak" (2225 only) or "Max . hold"
(2226 only) mode, press RESET (BATT.)
3.5.3. Noise Dose Measurements
What the instrument measures in the "60s L eq" mode is a noise dose referred to min-
ute . If this L eq is referred to a time duration of 8 hours by subtracting approx. 26,8 dB
( 1
0 log
10
(8 x 60)) it can be expressed as a percentage of the allowable dose for that pe-
riod. A nomogram for estimating the percentage of allowable noise dose for an 8 hour
working day from the meter reading is reproduced in Fig.3.5. This applies to ISO only.
Allowed 8 hours
Leq-value
80 dB
85
/
/
/
90
/
/
/
/
/
Noise dose in % of
max. allowable dose
/
/
/
800 /
400 /
/
200
/
100%
0
60s Leq -value dB
/
/
/
/
/
/
/115
110
105
100
95
90
SEL Value
125
780873
Fig . 3. 5. Nomogram for estimating daily noise dose or SEL(L Ax)
from meter reading
3.5.4. SEL(lAx) Measurements
12
SEL is the Sound Exposure Level and is basically an Leq normalised to a duration of 1
second. It is used primarily to rate individual noise events, either to compare them with
regard to annoyance, or to evaluate an overall noise climate by combining a number of
individual events whose level and frequency of occurrence are known. The procedure is
exactly as in 3 . 5.2, for "60s Leq" measurement, except that the reading may be taken
as soon as the event is over, without waiting for the full minute measuring period to
elapse. To this measured value just add approx. 18 dB ( 1 0 log
10
60) to convert to SEL
(LAx).

BRUEL & KJAER 2225 Specifications

General

Brand	BRUEL & KJAER
Model	2225
Category	Measuring Instruments
Language	English