Hearing Protection when dispensing liquid nitrogen from bulk tank, or simply existing in any (work area) location where the sound level exceeds 80 dB*.   Other operations likely to require hearing protection are operation of accelerator chains, power tools, impact producing hand tools such as hammers, the use of explosives, lathes (wood or metal), precision machining and metal-working equipment.    a means of attenuating noise to below damaging levels when and where it is not possible to reduce them through engineering.  Ear covers (also known as earmuffs or headsets) and insert-type earplugs (formable, premolded, or custom molded, of many different shapes and compositions) are the hearing protection devices which exist.  All staff exposed to noise requiring hearing protection must also participate in the Universities Hearing Protection program.  Contact REM at 46113. Earplugs: Always make sure your hands are clean before inserting earplugs.  Always read the instructions supplied with the earplugs.  Some earplugs – for example the compressible foam type – come in only one size. If the plugs are made in several sizes, you need the right size for each ear.  To insert plugs:

Reach around your head and take hold of the back of your ear about half way down Gently pull your ear outwards and upwards to straighten your ear canal Insert the plug into your ear canal with the other hand.

If plugs are compressible foam type:

Roll the plug slowly and smoothly into a thin crease-free cylinder (depending on how small you roll the plug, it can take up to 30 seconds to do this, possibly longer if you haven’t done it before) Immediately insert the plug well into the ear canal and hold it in place until it has begun to expand and block the noise. Aim to get three-quarters of the length of the plug into the canal.

Remember -- Plugs can work loose and may need to be repositioned occasionally.  Remove plugs slowly so that suction does not hurt your ear.  If the earplugs are disposable, they should not be reused. Earmuffs: Inspect the muffs and note which way they are meant to be worn. Some earmuff cups are marked top or front and should be worn that way.   Oval shaped cups are meant to be worn so that the oval is vertical. Extend the headband to its maximum length. Brush as much hair as possible away from the ears Place the muffs over the ears, making sure that the ears fit right inside the cups and are not pressed against the head Hold the cups firmly in place by pressing inwards and upwards with the thumbs and tighten the headband so that it takes the weight of the cups and holds them firmly in position Run your fingers around the cushions to check that they are making a good seal against your skin.

Proper hearing protection can only be chosen with the help of a professional.  The noise reduction ratio must be chosen for the work, after assessment, and the fit must be evaluated by someone who knows what he's/she's doing.   (Do not just go choose something and stick it on or in your ears.)  Earmuff performance may be degraded by anything that compromises the cushion-to-flesh seal, including other pieces of personal protective equipment such as eyewear, masks, faceshields, and helmets.   The maximum sound attenuation afforded by hearing protection devices is limited by human body and bone conduction mechanisms. Even though a particular device may provide outstanding values of noise attenuation the actual noise reductions may be less because noise surrounding the head and body bypasses the hearing protector and is transmitted through tissue and bone pathways to the inner ear. It takes two to three weeks to get used to wearing hearing protectors. Once you are used to them you will, feel less stressed while you’re working, feel less tired at the end of the day, and know your hearing is safe. Remember that hearing protection attenuates all sound, not just unwanted sound.  It is important to be able to communicate when something could be dangerous.  Earplug users may not be able to hear a shouted warning or the sound of moving machinery. If an earplug should break off in the ear, it may require professional removal.

Keep muffs and plugs clean with soap and water.  As soon as plugs become hard or damaged get a new pair.  Don’t stretch the headband of your earmuffs – it makes them less effective.  Replace the cushions on your earmuffs as soon as they start to harden.  If your earmuffs are damaged get the damaged part replaced.

* See noise comparison chart for info on decibel levels.  Contact REM to request noise level evaluation.  If hearing protection is waranted for your operation, they will advise on the best choice.