Instruction manual

119
Technical Notes
second), and L
x
processing is carried out every interval. The L
x
reading can therefore be
displayed already during measurement.
L
max
, L
min
(maximum and minimum sound pressure level)
L
max
is the maximum sound pressure level and L
min
the minimum sound pressure level
encountered during a measurement. In the NA-27, the sampling interval for A/D conver-
sion is 10 ms (100 samples per second), and the L
max
and L
min
values since the start of the
measurement are stored. Therefore the L
max
and L
min
readings up to the current point can
be displayed already during measurement.
L
tm3
, L
tm5
(Takt-max sound pressure level)
For the duration of the measurement, the maximum level within a 3-second or 5-second
interval is sampled and the power average is determined. L
tm
is calculated according to the
following equation.
Lm: Maximum level within interval (3 or 5 seconds)
N: Number of samples
The number of samples is determined according to the following equation.
For L
tm3
:
For L
tm5
:
t
1
: Measurement start time
t
2
: Measurement end time
* L
tm
is specified by DIN as "Taktmaximalpegel Mittelwert", and its meaning in En-
glish is "Power averaged maximum sound pressure level in a measuring period".
Lpeak (waveform peak hold)
The waveform peak sound pressure level for a given measurement interval can be mea-
sured.