Sound Level - General Advice - Castle group dBAir Operating Manual

Sound Level – General Advice
In some environments, high levels of noise can occur. The Castle dBAir sound level
meter has therefore been designed for complete accuracy up to sound levels of 140dB.
Before you record measurements, take the time to ensure you have chosen the
optimum range for the process to be recorded. Wherever possible, the optimum range
is when the average measured signal is approximately half way between the top of the
range and the bottom of the range without an overload condition.
Where high levels of noise are encountered, the meter may register an overload and in
these circumstances the meter will display that this has occurred, it is therefore
advisable to determine if an overload occurs on the selected range. In such cases, you
will need to select a higher range to accommodate the higher peak levels. See Technical
Specifications for peak range limits on each individual range.
If the noise levels are too low for the range selected, then the meter will display an under
range condition. Under these circumstances, you will need to select a lower range.
For more detailed information, see Overload and Under Range Conditions and
Measuring Ranges.
If measuring low level noise, then be aware of the inherent noise levels caused by a
combination of thermal and electrical noise from both the microphone and the sound
level meter. Measuring data that lies within 10dB of the lowest quoted level on the
lowest measuring range may be influenced by the self-noise of the system. See
Technical Specifications for inherent noise levels and range limits.
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