GB1423194A - Self-shaping earplugs - Google Patents

Abstract

1423194 Ear plugs A W MILLS 9 April 1973 16881/73 Heading A5R An earplug comprises an envelope defining two resilient cavity portions connected by a neck and containing a plastic filler material which is deformable under sustained pressures but unyielding to oscillatory accoustic pressures (e.g. waxes, gels, silicone resins or puttys), a stiffening member interconnecting the ends of the envelope. The stiffening member 30 is a rod or tube of solid or foamed plastics material and may serve to equalise pressures inside and outside the ear. The stiffening member may contain oil or grease to attenuate sound. The filler material may be formed directly on the stiffening member or on an inner wall 10a of the envelope which is bonded to the stiffening member, the outer wall 10b of the envelope being formed outside the filler material. Bored or hollow enlargements 32a, 32b which are joined to or made in one piece with the stiffening member may join the stiffening member to the envelope. The stiffening member may project from the plug at one end to provide a handle (40) Figure 6 (not shown). A metal or plastics cap (92) Figure 11 (not shown) may shield the enlargement (90) of the stiffening member, which is intended to be located outside the ear in use, from incident sound. For insertion of the earplug, one cavity portion is squeezed, to force filler material into the other cavity portion, and inserted in the ear by pushing on the stiffening member which thus pulls the envelope into the ear. The elasticity of the envelope tends to restore the inserted cavity portion to its initial shape so that the removed filler material flows back into it and thus the envelope bears against the walls of the auditary canal. The cavity portions may be generally spherical, ellipsoidal or have an irregular shape.