AS/NZS 1270 hearing protector classes explained
Ear plugs and earmuffs tested to the Australian standard are marked with a class from 1 to 5 and an SLC80 number. This page covers what those two figures mean, where they come from, and how to use them to pick a protector for a measured noise level.
Two standards, two jobs
AS/NZS 1270:2002 Acoustics: Hearing protectors is the test standard. It sets how a protector's attenuation (noise reduction) is measured. The result is printed on the packaging as a class and an SLC80 value.
AS/NZS 1269.3:2005 Occupational noise management, Part 3: Hearing protector program is the selection standard. It covers choosing, fitting and maintaining protectors, and it is the standard Safe Work Australia's Code of Practice says to select them under.
Both standards are sold by Standards Australia and we have not reproduced them here. The figures on this page come from the Code of Practice and from state regulators that publish the tables.
What SLC80 means
SLC80 stands for Sound Level Conversion, valid for 80% of wearers. It is the noise reduction, in decibels, that the rating is valid for across 80% of wearers. A plug rated SLC80 14 is expected to take 14 dB off for four in five wearers, and only if it is fitted properly and kept in.
Suppliers are expected to give the SLC80 rating, the class and the octave band attenuation values, all measured under AS/NZS 1270. A rating under the US Noise Reduction Rating (NRR) system is not a substitute: SafeWork NSW states NRR-rated protection is not acceptable in Australia because the test method differs.
The five classes
The class is a band of SLC80 values. Each band is matched to a range of measured eight-hour noise exposure (LAeq,8h), taken without counting any hearing protection.
| Class | SLC80 | Measured exposure, LAeq,8h dB(A) |
|---|---|---|
| Class 1 | 10 to 13 | less than 90 |
| Class 2 | 14 to 17 | 90 to less than 95 |
| Class 3 | 18 to 21 | 95 to less than 100 |
| Class 4 | 22 to 25 | 100 to less than 105 |
| Class 5 | 26 or more | 105 to less than 110 |
Exposure bands: Safe Work Australia Code of Practice, Table 4. SLC80 ranges: WorkSafe Victoria, which reproduces the classification table from AS/NZS 1269.3. The two sources agree on the exposure bands. The table stops at 110 dB(A).
Picking a class for a noise level
- Measure first. The input is a measured eight-hour exposure for the worker or area. SafeWork NSW puts it plainly: never guess the protection level needed.
- Read the class off the table. A measured 92 dB(A) sits in the 90 to 95 band, so Class 2. With an SLC80 of 14, that leaves about 78 dB(A) at the ear.
- Check it is not too much. The exposure standard is 85 dB(A) over eight hours, with a peak of 140 dB(C). SafeWork NSW recommends aiming for 80 dB(A) at the ear. WorkSafe Victoria advises not reducing exposure much below 75 dB(A), because over-protected workers struggle to hear instructions and warning signals.
- Pick one people will keep in. The Code's example: a protector giving 30 dB over a full eight-hour day falls to 9 dB if it is out for one hour.
The class method is the simple one. Where one frequency dominates, the octave band method in AS/NZS 1269.3 uses the protector's attenuation at each frequency instead, and needs measured data for the site.
Impulse noise has its own rule. The Code, citing AS/NZS 1269.3, says Class 5 protectors should be used for impulse noise from impacts, small-calibre weapons or tools, and earplugs of at least Class 3 plus earmuffs for large-calibre weapons and blasting.
Common questions
Is a higher class always safer?
No. The Code says not to provide protectors that overprotect, because cutting out too much sound makes it harder to hear instructions and other sounds needed to work safely.
Do hearing protectors come first?
No. They are the last control, after removing or reducing the noise itself. What a business is required to do is covered in WHS noise duties for employers, and the authority is Safe Work Australia and your state regulator. This page is not legal advice.
EarGuard makes a Class 2 reusable corded plug, SLC80 14 dB, for exposures of 90 to less than 95 dB(A).
Sources
- Safe Work Australia, Managing noise and preventing hearing loss at work: Code of Practice, November 2024 (PDF): exposure standard, Table 4 class selection, the 30 to 9 dB example, impulse noise guidance, over-protection.
- WorkSafe Victoria, Hearing protection: SLC80 range for each class, the 75 dB(A) over-protection guidance, the octave band method.
- SafeWork NSW, Hearing personal protective equipment (PPE): the facts: the SLC80 definition, the 80 dB(A) in-ear target, NRR not acceptable in Australia.
- AS/NZS 1270:2002 Acoustics: Hearing protectors, and AS/NZS 1269.3:2005 Occupational noise management, Part 3: Hearing protector program. Paywalled; cited through the sources above.