The Elliott Ear Protector acts on an entirely different principle and it reduces the noise of a heavy express rifle to a mere thump, like striking the fist on a wooden table. It takes all the sting out of the shot.
A man who was a gunner at the front during the war tells me that his ears are quite right owing to his having used the Elliott Ear Protectors, whereas a man standing next to him had an ear drum burst after a few shots.
The principle of this protector is to let the sound strike the side of the tube of the outer ear, instead of directly on the ear drum. The protector closes the ear tube so that only a very minute, hair-like passage remains, through which a whisper can come, but any big volume of sound is checked, like a crowd trying to push through a narrow door and allowed only to dribble in one at a time.
Even the small amount of sound which does get through is impinged on to the sides of the outer ear passage. None reaches the drum of the ear direct, but indirectly by the action of a rubber diaphragm.
The result is arrived at as follows:
A short celluloid rod has a hair thin hole running down it, but not quite reaching the far end. It enters a hole of the same size running across the tube.
There is a soft India rubber disc at each end of the rod, the transverse hole being between the two discs.
In use this rod is inserted into the ear till the uppermost disc just closes the passage into the external ear, and the lower disc cuts off access to the ear drum.
Any sound reaching the ear can therefore only pass down this hair thin passage in the rod and into the space between these two rubber diaphragms.
The sound cannot reach the ear drum. It passes through the transverse hole into the space between the two discs.