Australia Model Code of Practice Managing Noise and Preventing Hearing Loss at Work 5.3-USE: Use personal hearing protectors only where other more effective controls cannot eliminate or minimise the risk, as an interim measure, or as extra protection; ensure they are worn for the whole exposure period since even an hour unprotected collapses the effective attenuation; and for peaks above 140 dB(C) use the firearm-grade protection in AS/NZS 1269.3 Appendix B (class 5 for impulse noise from impacts and small-calibre weapons, class 3 earplugs under ear-muffs for large-calibre weapons and blasting)

What does 5.3-USE require?

Personal hearing protectors such as ear-muffs or earplugs are used when the risks from noise cannot be eliminated or minimised by more effective controls, as an interim measure until other controls are in place, and where extra protection is needed beyond what other controls achieve. Where they are necessary they must be worn throughout the period of exposure: removing them even briefly sharply reduces the effective attenuation, so that a protector giving 30 dB over a full eight hours gives only 9 dB if left off for one hour. Because peak levels above 140 dB(C) can cause immediate hearing loss, and regardless of higher-order controls, PCBUs should select the hearing protectors specified for firearms in Appendix B of AS/NZS 1269.3: class 5 protectors for impulse noise from impacts, small-calibre weapons or tools, and well-fitted earplugs of at least class 3 together with ear-muffs of any class for impulse noise from large-calibre weapons and blasting.