The Difference Between Class 1 & 2 Sound Level Meters

Monitoring Occupational Noise with Sound Level Meters

A sound level meter (SLM) is an instrument that monitors noise intensity. Sound level meters are generally small handheld battery-operated devices with a display, that utilise a microphone to pick up sound. The device then converts sound levels into electrical signals to display a quantitative reading.

Used for workplace noise evaluations and environmental noise assessments, common applications include industries with high sound exposure levels such as mining, occupational hygiene, and construction. These devices are important for monitoring noise to assist users in identifying hazards to workers’ health and safety to implement more effective risk management programs. Improving these programs can assist workplaces to:

• Protect workers from hearing loss and damage,
• Improve audio communication,
• Reduce the stresses associated with extreme noise in workplaces.

Sound level meters are available in two performance categories: class 1 and class 2. The performance categories are dictated by the International Standard IEC 61672-1:2002, which gives electroacoustical performance specifications for three kinds of sound measuring instruments, including specifying the two performance standards. The previous standard IEC 60651 refers to the categories as “types” with the current standards referring to the categories as “classes.” Both sets of categories are similar, however the newer standards have stricter requirements surrounding accuracy, performance and calibration.

Occupational Noise Exposure Standards in Australia

The Australian Work Health Safety (WHS) regulations set out specific occupational noise exposure standards that businesses need to adhere to ensure worker safety. There are two exposure standards for sound. The first is to prevent gradual loss over time and the second standard is to prevent immediate hearing loss due to extreme noise. The exposure standards in accordance with AS/NZS 1269.1 are:

• L_Aeq,8h of 85 dB(A) – This refers to the exposure of noise over a working day and takes into account both the noise level and length of time of the exposure.
• L_C,peak of 140 dB(C) – This relates to loud and sudden noises that can cause immediate hearing loss.

The Difference Between Class 1 and Class 2 Sound Level Meters

Class 1 sound level meters are considered a precision grade meter and meets a higher level of set performance criteria as dictated by IEC 61672-1:2002.

Class 2 sound level meters are considered a general grade meter and meets a lower tolerance level than the class 1 category. Class 2 meters are ideal for applications such as general monitoring and recreational noise monitoring where a higher level of precision and accuracy is not required. The tolerance levels for each reference frequency are as follows:

Considerations When Selecting a Sound Level Meter

When selecting an SLM, it is important to consider a range of factors inlcuding:

• Accuracy of the data required
• Regulatory requirements of the measurements
• Application of the data recorded
• Optional accessories and instrument add-ons

Air-Met Scientific’s range of sound level meters are available for sale and rental and perfect for varying applications. Our range includes: