Hearing Protection Selection & Class system

The choice of hearing protection depends on a number of factors, including the level of noise, comfort and suitability of the hearing protection for both the worker and the environment. Most importantly, the hearing protection should provide the desired noise reduction.

It is best, where protection must be used, to provide a hcoice of a number of different types of hearing protection. each device is given a class rating from 1 to 5 to show the level of noise reduction achieved.

What is dB?

dB stands for Decibel, the unit of sound level and noise exposure measurement.

When is hearing protection required?

Exposure to noise levels above 85dB can cause permanent hearing loss and therefore hearing protection is required. A workplace noise assessment should be carried out to ascertain noise levels at different sites.

What is the class system and SLC rating for hearing protection devices?

The class system for hearing protection devices is categorised according to an attenuation (reduction) or Sound Level Conversion (SLC80) rating and the noise level at which they remain effective. It is derived from a test procedure outlined in the Australian/New Zealand Standard AS/NZS 1270.

The SLC value includes a correction to ensure that the stated degree of noise reduction is obtained on 80% of occasions. Hence the (SLC ) rating. This rating is the difference between the sound level of the environment in which the hearing protection device is worn and the sound level reaching the wearer's ears. The higher the rating, the greater the efficiency of the hearing protection device.

Class System for Hearing Protection Devices
Class SLC Range (dB) For Use in Noise
Levels (dB(A))
General Examples
1 10 - 13 < 90 Loud Radio, Busy Traffic
2 14 - 17 90 - <95 Power Lawn Mower,
Belt Sander
3 18 - 21 95 - <100 Tractor, Electric Drill
4 22 -25 100 - <105 Bulldozer, Heavy Machinery
4 22 -25 100 - <105 Bulldozer, Heavy Machinery
5 26+ 105 - <110 Blasting, Nail Gun

Please Note:

This table is a general guide only and is not an absolute basis for noise level selection as some equipment may operate at different noise levels. Detailed workplace noise assessments should be carried out by a qualified person.