Protectors that reduce the level at the ear to below 70 dB should be avoided, since this over-protection may cause difficulties with communication and hearing warning signals. Users may become isolated from their environment, leading to safety risks, and generally may have a tendency to remove the hearing protection and therefore risk damage to their hearing.

The table below gives an indication of the protector factor that is likely to be suitable for different levels of noise (the noise level during a particular work task, not the daily personal noise exposure). It is based on the single number rating (SNR) value provided with a hearing protection device. The information is intended as a guide rather than a substitute for using one of the standardised methods for calculating hearing protection performance, and in particular will not be appropriate if there are significant low-frequency components to the noise in question. Examples of noise environments which may contain significant low-frequency components, and for which this table is not suitable, include press shops, generators and generator test bays, plant rooms, boiler houses, concrete shaker tables, moulding presses and punch presses.

Indication of protector factors:

A-weighted noise level (dB) Select a protector with an SNR of …


20 or less






30 or more

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Updated 2010-02-02