Hearing Protection

The human ear is designed to be able to absorb natural sounds. Because people developed equipment and did inventions, the sound spectrum expanded with a wide range of unnatural sounds that the ear can not properly process. The sensory cells (stereocilia) in the ear degenerate if they are repeatedly exposed to excessive noise. The sensory cells that remained can only transfer part of the sound information. Therefore, a permanent hearing loss is a fact. In the popular speech this is called deafness by noise.

Good hearing protection is therefore essential. Good means: not too little, but not too much attenuation. The hearing protection must also be maintained and worn properly.


Standards and legislation

Hearing protection must comply with the technical standard EN 352: 2002. This has been developed for different resources:

• EN 352-1, for ear-muffs

• EN 352-2, ear earplugs and ear moulds

• EN 352-3, for variants such as earmuffs attached to safety helmets

• EN 352-4, level-dependent ear-muffs

• EN 352-5, for the active noise-reducing ear-muffs

• EN 352-6, for hearing protectors with electrical audio output

The international standard ISO 4869-1 applies for the determination of the sound attenuation and ISO 4869-2 for the calculation of the sound attenuation.

There are important so-called limits within the law:

• Noise 80 dB(A)

• Noise 85 dB(A)

• Noise 87 dB(A)


Exposure of Sound Pressure Level in dB(A)

8 hour 80 dB(A)

4 hour 83 dB(A)

2 hour 86 dB(A)

1 hour 89 dB(A)

30 Minutes 92 dB(A)

15 Minutes 95 dB(A)

7 minutes 30 seconds 98 dB(A)

3 minutes 45 seconds 101 dB(A)

2 Minutes 104 dB(A)

1 Minutes 107 dB(A)


Each limit has its own actions:

Noise 80 dB(A)

• Definition of risk

• Responsible to take measures to reduce exposure

• Inform the staff of the risks

• To ensure training and information about the risks and possible measures

• Audiometric testing is required if the risks may endanger health


Noise 85 dB(A)

• All the above mentioned points

• Hearing protection is required

• Audiometric testing is a requirement

Noise 87 dB(A)

• This limit may not be exceeded

• The sound level is measured in the ear, this must be taken into account with the hearing protection

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