Under what condition must double hearing protection be used?

Double hearing protection is required when single hearing protection fails to adequately reduce sound energy levels to 85 dB or less. This situation typically arises in environments where noise levels are dangerously high, and the risk of hearing damage is significant.

In this context, using single hearing protection, such as earplugs or earmuffs, may not provide sufficient attenuation of sound, particularly in louder environments. Hence, to mitigate the risk of hearing loss, double protection—combining both earplugs and earmuffs—becomes essential to create a more effective barrier against harmful noise levels.

This standard aligns with workplace safety regulations aimed at protecting workers in high-noise environments. While working near machinery, high sound levels (like above 90 dB) and the use of power tools can definitely necessitate hearing protection, it is the specific requirement to achieve a sound level of 85 dB through adequate protection that defines when double protection is mandated.