"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 - Type 1 is more accurate than Type 2. The ANSI S1.4 and 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.

* 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, most occupational noise measurement regulations state that the lower cost Type 2 or Class 2 meter is adequate. Of course you can use a Type 1 meter if you prefer as it is more accurate.

There can be other reasons for selecting the class of meter. Our Type 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 Type 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.

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