AS/NZS 1270:2002:
Acoustics – Hearing protectors
This Standard specifies requirements for the design, materials, and performance of conventional hearing protectors. It also provides guidance on the general requirements for, and the physical and acoustic testing of, specialist hearing protectors.
Under the Australian Standard AS/NZS 1270:2002, the class is an easy way to choose a hearing protector appropriate to a noise exposure. The standard rates hearing protection into five classes, with Class 1 being the lowest level of protection and Class 5 being the highest level.
The system is based on the SOUND LEVEL CONVERSION (SLC₈₀) rating which is 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. This is converted to a Recommended Noise Range.
To use the right hearing protectors, it is necessary to know the employee’s’ eight hour exposure level (LAeq8h) and then select the class of protector as indicated in the table below. The corresponding SLC₈₀ values are also shown in the table below.
Relationship between class and SLC₈₀ of hearing protectors:
| Class | SLC₈₀ range | LAeq 8hr dB(A) |
| 1 | 10 – 13 | Less than 90 |
| 2 | 14 – 17 | 90 to less than 95 |
| 3 | 18 – 21 | 95 to less than 100 |
| 4 | 22 – 25 | 100 to less than 105 |
| 5 | 26 or greater | 105 to less than 110 |
LAeq = Equivalent Continuous Sound Pressure Level
dB (A) = The louder the noise, the higher the decibels. Decibels can be adjusted to human hearing. Noise level is thus described in decibels A (dBA).
Between 80 and 85 dB(A), hearing protection is advisable if your exposure is unusually long, or if you engage in other loud activities throughout the day. For noise under 82 dBA, hearing protection is not required but may be used.
For example:
LAeq,8h of 85 dB(A) means that an unprotected worker cannot be exposed to more than 85 decibels continuously over an eight-hour shift. The permitted time of exposure for an unprotected worker decreases as the noise exposure level increases
