Cause and effect of using silicone based hearing protection

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sil·i·cone (s l -k n )
n.
Any of a group of semi-inorganic polymers based on the structural unit R2SiO, where R is an organic group, characterized by wide-range thermal stability, high lubricity, extreme water repellence, and physiological inertness and used in adhesives, lubricants, protective coatings, paints, electrical insulation, synthetic rubber, and prosthetic replacements for body parts (http://www.thefreedictionary.com/silicone).

So, what is said about silicone ear devices?
These devices are custom moulded in a silicon material. Each ear mould is individually made to offer maximum comfort and protection. They are non-allergenic and hygenic. All of our ear protectors are manufactured to an extremely high quality and are C.E. certified. (http://www.audi-lab.com/earprotectors.htm).
Yet another says this,
First, silicone plugs are made of skin-soft materials are carefully custom fitted. Each protector follows the exact configurations of an individual's ear, and tightly occludes without discomfort. They have no pressure points, no hot spots, no sound leaks, and no chance of being poorly seated in the ear (which would lower effectiveness).
Second, silicone plugs have no working parts to wear out or break down. Along with the custom mold, they are non-toxic, anti-allergenic, and 100% safe. A channel in the ear mold guarantees permanent placement and optimum noise reduction.
Custom silicone earplugs are so comfortable and so effective that worker acceptance is extremely high. Employees find they can carry on normal conversation, answer telephones, hear alarms, even machine malfunctions, change elevation and move from high to low noise levels without adjusting or removing the ...