Instruction Manual

Sound Level Meter Types 2245 – Instruction Manual Page 56 of 110
Fig. 4.14 Typical self-generated noise, 1/3 octave band
4.9 Measuring Ranges
The Upper Limit in the following sections is based on the guaranteed worst-case limit
for the sound level meter and the nominal Open Circuit Sensitivity of the microphone.
The Overload Limit can, due to tolerances in the sound level meter, be up to 1.5 dB
higher than the worst-case limit, but tolerances specified in the international standards
are maintained as long as no Overload is indicated.
The Lower Limit in the following sections is based on the guaranteed worst-case limit
for the sound level meter, the nominal open circuit sensitivity of the microphone, under
Reference Environmental Conditions, Measurement settings > Input > Sound Field
set to Free-field and no microphone accessories selected.
4.9.1 Maximum Sound Level
The maximum Sound Level that the sound level meter can accommodate without
causing damage to the sound level meter: 158 dB Peak.
4.9.2 Total Range
Total Range is defined as the difference between the Upper Limit on the least sensitive
level range, and the lowest sound pressure level measurable on the most sensitive level
range, which can be measured at 1 kHz within the most conservative tolerance limits,
specified in the international standards IEC 61672–1, IEC 60651 and IEC 60804:
Table 4.3 Total Range
Please note: For Sound Exposure Levels, the stated ranges are valid if 10*lg(Δ t ) is added
to the limits. Δ t being the averaging time interval, indicated as Elapsed
Time , expressed in seconds.
A-weighting
(dB)
B-weighting
(dB)
C-weighting
(dB)
Z-weighting
(dB)
140.9 - 22.7 140.9 - 22.4 140.9 - 24.9 140.9 - 31.6
Frequency Weighting