"Type" or "Class"
of a Sound Level Meter
The Type or Class of a sound level meter describes
its accuracy as defined by the relevant international standards - Class
1 is more accurate than Class 2. The older standard IEC 60651 referred
to the grade as "Type", whereas the new standard IEC 61672 refers to
it as the "Class". Although these standards have similarities, the
later standard does make more demands on the meter regarding accuracy,
performance and calibration.
Although older meters meeting the IEC 60651 (and IEC 60804) can continue
to be used for most applications, when purchasing a new meter you should
get one that meets the new standard IEC 61672.
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Grade |
Definition |
Tolerance* |
Typical Applications |
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Type 1 / Class 1 |
Precision Grade for laboratory and field use |
± 0.7 dB |
Environmental, building acoustics, road vehicle |
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Type 2 / Class 2 |
General Purpose Grade for field use |
± 1.0 dB |
Noise at work, basic environmental, motor sport |
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* These are the tolerances under reference conditions as defined in
the IEC 60651 standard, section 9.1.
The class of meter that you need will depend on your application and
on any regulations that you need to meet. For example, the European
Noise at Work Regulations state that the lower cost Class 2 or Type
2 meter is adequate. Of course you can use a Class 1 meter if you prefer
as it is more accurate.
There can be other reasons for selecting the class of meter. Our Class
1 meters tend to measure lower levels due the sensitivity
of the microphone capsule. This is particularly relevant for environmental
noise surveys where low noise levels are being measured. Finally, you
may choose Class 1 for important legal applications as the evidence
from the more accurate meter may be more convincing, even when the
regulations do not demand it.
< Acoustic Terms Index
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