AS/NZS 1270:2002

Acoustics - Hearing Protectors

This standard specifies requirements for the design, materials, and performance of conventional hearing protectors. It also guides the general requirements and physical and acoustic testing of specialist hearing protectors.
Over-exposure to dangerous noise levels at work can lead to hearing loss, some of which can be permanent. Each day we are exposed to varying levels of noise in both the workplace and at home. Noise levels are measured in decibels (dBA), and prolonged exposure to levels over 85 decibels over 8 hours may cause irreparable hearing loss. Understanding your work environment and the different noise levels gives you the best chance of minimising damage.
Under the Australian Standard AS/NZS 1270:2002, a ‘class’ system is an easy way to choose a hearing protector appropriate to noise exposure. The standard categorises hearing protection into five classes, with Class 1 being the lowest level of protection and Class 5 being the highest level.

SLC80 (Sound Level Conversion)

An SLC80 (Sound Level Conversion) rating is engaged in converting the difference between the sound level of the environment in which the hearing protection is worn and the sound level reaching the wearer’s ears. Under the standard, people should not be exposed to sound above 85dB for more than an 8 hour period. A noise survey is then conducted, and the table to the right is used to select the appropriate Class of hearing protection required. By way of example, if a person is working with a hammer drill running at 114dB, then the noise must be reduced to 85dB or less; therefore, Class 5 26dB+ hearing protection would be essential. The home scale below shows decibel ratings of various objects you could contact, whereas the work scale indicates when these decibel levels start damaging your hearing.

ClassSLC80 dBNoice Survey Result
110-13Less than 90dB (A)
214-1790dB to less than 95dB (A)
318-2195dB to less than 100dB (A)
422-25100dB to less than 105dB (A)
526+105dB to less than 110dB (A)

Home Scale Decibels (dBA)

Decibel scale based on items you would find in and around the home.

Work Scale Decibels (dBA)

Decibel scale for workplaces, indicating when action is required to be taken.