Slow recovery earplugs, such as the type described in U.S. Pat. No. Re. 29,487 have gained wide acceptance. Such earplugs can be rolled in the fingers to a small diameter, inserted into the ear, and allowed to expand over a period of between a few seconds to a few minutes to completely fill the end of the user's ear canal. Such earplugs have been previously formed by punching cylinders out of a thick sheet of slow recovery material, which is generally an open cell foam that allows air to escape when squeezing the earplug before insertion. Such earplugs easily pick up water or other fluids which hamper their use. Also, the multiple cut cells at the surface tend to pick up dirt, especially when a worker with dirty hands rolls the earplug between his fingers to compress it prior to insertion. A slow recovery earplug which resisted soiling and the pickup of water at its surface would be more sanitary and have a longer lifetime of use.
USPTO Backgrounds
USPTO Backgrounds