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Preamble As the ear is the most sensitive human organ, most governments have issued laws and regulations in order to protect workers against dangerous noise exposure. In general, hearing conservation devices have to be used by workers who are exposed to more than 85 decibels (“dB”) during eight hours of work. Noise is an unpleasant, aggravating and debilitating problem. Damage to the tiny sensory hair cells in the ear is irreversible. Personal hearing loss can lead to expensive compensation claims being lodged against employers. The source and level of noise must be detected and analysed. As a part of risk assessment a noise meter should be used to monitor the sound level. SNR (Single Number Rating) SNR is only a general means of comparing different ear muffs. Generally the higher the SNR number, the better the performance of the ear muff across a range of noise frequencies, for example: a SNR of 30 may not give a 30 dB attenuation at all frequencies. The figures associated with H, M and L indicate the level of protection within the range of High, Medium or Low frequency noise. Examples (as a guide only): For the wearer of an ear muff where H=35 a high frequency noise of 100 dB will drop to 65 dB. Wearing the same ear muff, where M=25, a medium frequency noise of 100 dB will drop to 75 dB. Since 2006, a new feature has become legal, which is the daily exposure limit value. It defines the maximum limit of noise that must not be exceeded at work after all control measures have been implemented. The level at which employers must provide hearing protection and hearing protection zones is now 85 dB (daily or weekly average exposure) and the level at which employers must assess the risk to workers‘ health and provide them with information and training is now 80 dB. There is also an exposure limit value of 87 dB, taking account of any reduction in exposure provided by hearing protection, above which workers must not be exposed. The following diagram shows various noise levels and their hazards to the ear: The sound energy doubles every 3 dB. Hearing conservation devices can basically be divided into two types: ➤ Ear Plugs (for use IN the ear) ➤ Ear Muffs (for use OVER the ear) 1.0 Ear Plugs Ear plugs can be made either of moulded plastics, or polymer-foam. They ensure comfortable wearing and can be used for works involving light or medium noise exposure. They are inexpensive and disposable; therefore high hygienic standards can be met. Foam Ear Plugs are made of expandable slow recovery foam that helps provide the best combination of comfort and protection for most users. Typically foam plugs are rolled down prior to insertion where the foam plug expands to provide a snug and secure comfortable fit. Moulded Ear Plugs are made of flexible materials that are preformed to fit the ear canal. These reusable ear plugs are comfortable, hygienic and economical. Detectable Ear Plugs are available in either a foam or a moulded finish. The ear plug is fitted with a choice of detectable components (steel ball or a non-ferrous filter) finished with a visible non food blue detectable cord. Banded Semi-Aural Ear Plugs can be finished in either a foam or moulded tip. Ideal for intermittent use as they are quick to put on and take off as well as being easy to store around the neck. They provide less protection than either plugs or ear muffs. 2.0 Ear Muffs Ear muffs are more expensive than ear plugs. They consist of two plastic ear cups, foam filled ear seals, damping pads and an adjustable headband. The ear seals cushion around the ear to block out noise. Ear muffs may be used for works involving higher noise exposure. They can be worn over the head, in combination with head protection devices or behind the head. Several models for headwear attachment can also be offered, either with the “CONNECT” or “SLOT” system. Choosing the correct hearing protection for your needs can be a difficult process. You need to be certain that you are providing the correct level of protection for the noise level. You need to ensure that workers are not 85 dB Forklift 87 dB Protection recommended for 8-Hour exposures above this level 80 dB Hand Saw 85 dB Protection recommended for 8-Hour exposures above this level 75 dB Vacuum Cleaner 74 dB Non-Hazardous 160 dB Apollo Lift-off 188 dB Immediate physical damage 140 dB Jet Engine Take-off 150 dB maximum allowable exposure 130 dB Impact Drill 130 dB Immediate pain threshold 120 dB Oxygen Torch 121 dB Short exposures at this level may cause hearing damage 100 dB Impact Wrench 102 dB Extremely loud 30

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