Explaining Class 1 and Class 2 sound level meters: Which type of device will you need?

Sound level meters are compact, hand-held devices that are used to measure noise. A microphone located in the unit responds to alterations in air pressure, generated by sound waves. The device accurately converts the measurement into a reading displayed on a screen on the sound level meter.

These easy-to-use, accurate and cost-effective noise measurement instruments are commonly used in environments requiring the measurement of the intensity of the noise being produced in the area, particularly for environmental, industrial and aircraft noise.

Standards stipulated by the IEC (International Electrotechnical Commission), the world’s leading organisation centred on the preparation and publication of global standards for all electronic and electrical related technology, divide sound meters into two different classes. These two different classes of noise meters are designed for the same functionality.

However, what is different between the two classes is the tolerances for error.

Noise meters are divided into a Class 1 noise meter and a Class 2 noise meter. So, what are the different tolerances for error between the two sound meter instruments?

A Class 1 sound level meter has a broader frequency range compared to a Class 2 instrument. A Class 1 sound meter also has a tighter tolerance than their Class 2 equivalents. By having a wider frequency range and a tighter tolerance, a Class 1 noise meter costs more than Class 2 units. A Class 1 acoustic calibrator used to calibrate a Class 1 noise meter are typically costlier than calibrators associated with Class 2 noise meters.

What are Class 1 sound level meters used for?

Standards and legislation involving noise standards usually allow the use of a Class 2 noise meter unit. Given the additional cost, the higher frequency range and the tighter tolerance, a Class 1 sound level meter is often used for law enforcement and research purposes.

Which Class of sound level meter should you use?

When deciding whether you require a Class 1 sound level meter or a Class 2 instrument, it is important to determine what exactly it is you are required to measure. You should then look for a sound level meter that caters for your requirements and will be sufficiently accurate to achieve the standards of noise measurement you require.

It is also important that you refer to any guidelines, standards or regulations you are required to meet. Different noise legislation and standards stipulate the use of a certain instrument with a particular degree of accuracy. It is also important that the device is calibrated with the right class of calibrator to retain its accuracy.

For example, if the noise regulations stipulate you must use a Class 1 sound meter to measure a specific environment, a Class 1 acoustic calibrator must be used to ensure the Class 1 noise meter is calibrated accurately.

If the standards and legislation you are working with refer to outdated instrumentation standards, it is important to contact the organisation to ask to be informed of the new standards regarding the Class of sound level meters required to meet that particular standard.