Abstract: The hearing aid system includes a hearing aid case which is designed to be positioned behind the ear of a user, a tube for conducting sound from the case to the ear canal of the user, and a eartip for anchoring the end of the tube within the ear canal of the user. The tube is formed in a preformed shape of a material with sufficient rigidity to support the hearing aid in a proper position on the user's ear. The eartip may be one of several different designs which secures an end of the tube in place in the ear canal in a comfortable manner without the need for an expensive custom made ear mold and without complete occlusion of the ear canal. A combination of the light weight and small size of the case, the rigidity of the preformed tube, and one of the eartips for anchoring the tube in the ear canal allow the system to be held in place securely without the need for either an inflexible and aesthetically unpleasing ear hook or an expensive custom made ear mold.

Abstract: A hearing aid circuit includes a correlation detector that detects correlation at a feedforward path input and that provides a correlation output to a phase shifter. The phase shifter introduces a phase shift along a feedforward path. A phase measurement circuit measures a phase shift at a feedforward path input, and provides a phase measurement output to an internal feedback processor. The internal feedback processor adjusts internal feedback as a function of the phase measurement to suppress coupling of external audio feedback along the feedforward path.

Abstract: An improved, laminated, ophthalmic lens structure, and method of producing the structure. The structure comprises two adjacent layers of dissimilar, organic plastic materials, either or both of which contain matter that tends to migrate. The improvement comprises a barrier layer that is intermediate the adjacent organic plastic layers; that is impermeable to migrating matter; and that is composed of a polyolefin polymeric material modified by the presence of acid or anhydride functional groups.

Abstract: A method of producing a glass-plastic, laminated, ophthalmic lens structure in a continuous operation. A thin, flexible, plastic adhesive layer is applied to a glass element to form a composite body that is inserted in a cylindrical gasket in such manner as to fit snugly and be sealed from the ambient. A monomeric formulation is flowed onto the adhesive layer and cured to form a laminated lens blank.

Abstract: An ophthalmic lens embodying an organic plastic lens member having a refractive index of at least 1.56 and being the cured product of a monomeric formulation. The formulation contains a resin monomer base, a curing agent selected from aromatic anhydrides, aromatic diamines, thioamides and thioamines, and a refractive index enhancing additive selected from alkyl or aromatic diols or thiols and transition metal alkoxides. The organic plastic lens member may be an integral, monofocal lens, or a segment embedded in a cavity in the front, convex surface of an organic plastic, major lens member having a lesser refractive index. The latter may have a thin, inorganic glass lens member adhered to its front, convex surface to produce a glass-plastic, laminated, multifocal lens structure.

Abstract: There is disclosed an improvement of the three layer laminated lens structure of U.S. Pat. No. 4,793,703 whereby the adhesive inerlayer is more tightly bonded to the outer plastic and glass layers by reactive groups on the surfaces of each layer. This controls a problem of delayed delamination.

Abstract: This invention relates to flame-retardant phosphorus-containing materials, particularly suitable for use as an additive, having little or no plasticizing effect, in flammable organic plastics. One such material may be made by reacting methallyl chloride with phenol or phenol-isopropylphenol blend and then phosphorylating. Another such material may be made by halogenating isopropyl groups of an isopropylphenyl phosphate blend and then dehydrohalogenating to make an isopropenyl-containing product, which may be oligomerized as by heating with a catalyst. The isopropenyl-containing product may also be employed as a flame-retarding comonomer.