Too much or not enough?


Ear muffs and plugs should be chosen according to the amount of protection that you need. This should take into account the expected intensity (noise level) in the area where they are to be used, as well as the amount of time a person will be expected to work in that area (exposure time).

How much hearing protection do you need?

All hearing protection devices come with a rating or classification that indicates the amount of sound dampening that they give.  Prior to 1998 this was called the SLC80 rating.  In 1998 this rating was revised and a new Australian / New Zealand standard (AS/NZS 1269.3 1998) was released.  With the introduction of this new "Classification Method" hearing protector selection was simplified.  Both classification systems are described as some farmers may have ear muffs purchased prior to 1998.

The "old" SLC80 rating:

"SLC" stands for sound level conversion, while the 80 implies that adequate protection should be supplied to 80% of the population when hearing protection is correctly worn.  The level at which you can be exposed to a noise for an 8 hour period without damage to your hearing is 80 dB.  To work out which level of hearing protection meets your needs, estimate the noise level of your working environment, eg chainsaw 120 dB, tractor without a cab 100dB.  Now subtract the 80dB (the target "safe" noise level), and the resulting number will be the SLC80 rating that you will need.

Protection needed for farming activities

Example 1 : 
working on a tractor without a cab all day.

estimated noise level
subtract target (safe) level
"SLC80 rating" protection needed

100 dB
-80 dB
 20 dB


Example 2:
working with noisy workshop tools all day.

estimated noise level
subtract target (safe) level
"SLC80 rating" protection needed

110 dB
-80 dB
 30 dB


The "new" Classification Method:
The "Classification Method" takes into consideration the safe target of 80 dB over an 8 hour day and makes reference to the intensity levels of the presenting sound.  Simply, the method requires the individual to estimate the level of sound and then refer to a simple chart which categorises the level of protection needed from 1 to 5.  This table is as follows

Hearing Protector Classification


Presenting Intensity (dB)

1 less than 90
2 90 to less than 95
3 95 to less than 100
4 100 to less than 105
5 105 to less than 110


Generally for most farming activities a moderate level of protection is adequate, eg SLC 80 rating : 20 - 25dB; Classification Method : 3 or 4.  Higher levels of protection should always be worn when working with very loud equipment, such as angle grinders and firearms, eg SLC 80 rating 30-32; Classification Method : 5.


Workplace Considerations
In some working environments too much or not enough protection can be uncomfortable, or even dangerous.

Too much protection can make conversation and warning signals hard to hear, and may cause feelings of isolation and the extra weight and strength of earmuffs may cause discomfort.  .

Not enough protection may provide no benefit and cause fatigue and noise injury.  Find out more about noise and fatigue on our "Noise and Fatigue" Fact Sheet.


For more information please contact the Farm Noise & Hearing Network.
Copyright 1998 Farm Noise & Hearing Network

Australian made hearing aids utilizing Swiss technology
proudly sponsoring the Farm Noise and Hearing project to promote the
prevention of hearing loss in our community

Copyright 1998 Farm Noise & Hearing Network