Method of manufacturing an in-the-ear hearing aid, auxiliary tool for use in the method

Abstract: In a method of manufacturing an in-the-ear hearing aid (25) a mould (23) is made of an ear canal (7) of an ear (3), which mould is used as a moulding die for the manufacture of a housing (27) of the hearing aid (25). When the mould (23) is made an auxiliary tool comprising a flexible tube (11) with a flange (13) at one end is inserted into the ear canal up to at least the proximity of a tympanic membrane (9) of the ear. Subsequently, a curable material (19) is introduced into the ear canal (7), the material pressing the flange (13) against the tympanic membrane (9), which precludes the ingress of material between the flange and the tympanic membrane. After the material (19) has cured the mould (23) with the tube (11) and the flange (13) is removed from the ear canal (7). During removal of the mould (23) the space between the tympanic membrane (9) and the mould is in communication with the outer air via the tube (11), so that no partial vacuum is produced, which may give rise to damage to the tympanic membrane (9). The mould (23) thus obtained is used as a moulding die for the manufacture of a custom-made in-the-ear hearing aid (25).

Description: The invention relates to a method of manufacturing an in-the-ear hearing aid for insertion into an ear canal of a person in proximity to a tympanic membrane, which method employs a mould of the ear canal of the person's ear, which mould is used for making a moulding die for the manufacture of a hearing-aid housing, comprising the steps of: inserting an auxiliary tool comprising a flexible tube having an opening at one end and a flange at another end into the ear canal with the flange in the ear canal in order to form the mould, thereafter introducing a curable material into the ear canal and, after the material has cured, removing the material with the tube and the flange from the ear canal. The external shape of such an in-the-ear hearing aid should correspond to the shape of the ear canal. In order to determine the shape of the ear canal moulds are made of the ear canal of a person. These moulds define the dimensions of hearing-aid housings to be manufactured. A method of making an ear mould is known from US-A 3,440,314. The known ear mould described therein is used for holding a hearing-aid receiver. In the prior-art method the flange closes the tube at one end and the tube is inserted into the ear canal over a part of the length of the ear canal. Subsequently, the tube is filled with a liquid metal which after solidifying keeps the tube in position. After removal of the mould the solidified material and the flange are removed and the tube serves as the acoustic duct. Since this receiver is not fitted in the ear canal the ear mould is formed over only a part of the ear canal. In modern hearing aids the hearing aid is situated near or against the tympanic membrane of the ear. If such a hearing aid is to be custom-made a mould up to the tympanic membrane is required. If the prior-art method would be used for making an ear mould up to the tympanic membrane a partial vacuum would be produced between the tympanic membrane and the ear mould during removal of the mould, so that removal would be painful or might even cause damage to the tympanic membrane. Ear moulds up to only half the length of the ear canal do not present this problem because the partial vacuum which can be produced is much smaller owing to the large volume of air in the rear part of the ear canal. Moreover, when such ear moulds are removed the ear canal is deformed at the location of the mould, for example by pulling at the auricle, thereby admitting air past the ear mould to the space between the ear mould and the tympanic membrane. This is not possible in the case of ear moulds which extend up to the tympanic membrane because starting from the tympanic membrane the ear canal is surrounded with non-deformable bony tissue over some distance, so that this part of the ear canal cannot deform. It is an object of the invention to provide a method of the type defined in the opening paragraph, which enables the ear mould to be removed without pain and without the risk of damage to the tympanic membrane. To this end the method in accordance with the invention is characterised by the steps of: using a flange having an opening situated opposite the opening of the tube so that the tube is open at both ends, bringing the tube with the flange into the proximity of the tympanic membrane in the step of inserting the auxiliary tool such that the step of introducing the curable material (19) presses the flange against the tympanic membrane, thereby precluding the ingress of material between the flange and the tympanic membrane. During removal of the ear mould the space between the tympanic membrane and the ear mould thus communicates with the outer air via the tube and air can enter the space, so that no partial vacuum is formed. An embodiment of the method in accordance with the invention is characterised in that before the tube is inserted into the ear canal the tube is closed at its end remote from the flange, and before the mould is removed from the ear canal the tube is opened at that end. This measure reduces the likelihood of the tube being obstructed in that curable material leaking between the flange and the tympanic membrane enters the tube. By closing the tube at the further end the pressure in the tube increases during insertion of the tube into the ear canal, which reduces the likelihood of curable material entering the tube. The invention also relates to an auxiliary tool comprising a flexible tube having an opening at one end and a flange at another end for making a mould for a housing of an in-the-ear hearing aid and intended for use in the method in accordance with the invention. The auxiliary tool in accordance with the invention is characterised in that the tube and the flange form an integral unit, the flange having an opening situated opposite the opening of the tube so that the integral unit is open at both ends, and the flange being flexible and thin enough so that, after insertion into the ear canal, the flange conforms to the shape of the tympanic membrane upon introduction of the curable material into the ear canal. Said integral unit reduces the likelihood flange being severed from the tube during insertion of the tube with the flange into the ear canal. It is to be noted that WO-A 9003089 discloses an apparatus and a method for conveying amplified sound to an ear, wherein use is made of a tube being an acoustic conduction tube. This tube is attached to a concha fitting which is connected to an hearing aid. The hearing aid has a flange tip which is affixed to said conduction tube at a distance to the tympanic membrane of the ear in order to create a resonant cavity. The invention will now be described in more detail, by way of example, with reference to the drawings. In the drawings: Fig. 1 is a sectional view of a head at the location of an ear with a tube on the ear canal, Fig. 2 is sectional view similar to that of Fig. 1, with curable material in the ear canal, Fig. 3 is a sectional view similar to that of Fig. 2, the ear mould being partly removed from the ear canal, and Fig. 4 shows an in-the-ear hearing aid manufactured by means of the method in accordance with the invention. Fig. 1 is a sectional view of a head 1 at the location of an ear 3. The ear 3 has an external auricle 5 and an internal ear canal 7, which at one end is terminated by a tympanic membrane 9. To manufacture an in-the ear hearing aid, which is introduced into the ear canal against or in the proximity of the ear canal, it is necessary to form a mould of the ear canal in order to define the shape of the hearing aid to be manufactured. In order to form a mould of the ear canal 7 up to the tympanic membrane 9 a flexible tube 11 having a flange 13 at one end is inserted into the ear canal 7 up to a point near or against the tympanic membrane 9 of the ear 3. The flange 13 is of a flexible material and is thin, so that the flange 13 conforms to the shape of the tympanic membrane 9. The flange 13 has an opening 15 (see Fig. 3) opposite the opening 17 at the end of the tube, so that the tube 11 is open at both ends. Before the tube 11 is inserted into the ear canal 7 and before a curable material 19 is introduced into the ear canal 7 to form the mould, the tube 11 is closed by means of a plug 21 (see Fig. 2) at the outer end, which reduces the likelihood of the tube 11 being obstructed by the curable material 19 leaking between the flange 13 and the tympanic membrane 9. By closing the tube 11 the pressure in the tube 11 increases during insertion of the tube 11 into the ear canal 7, which reduces the likelihood of curable material 19 entering the tube. Subsequently, the curable material 19, for example a two-component silicone compound, is introduced into the ear canal 7, the material 19 pressing the flange 13 against the tympanic membrane 9, which precludes the ingress of material 19 between the flange 13 and the tympanic membrane 9. After the material 19 has cured the mould 23 with the tube 11 and the flange 13 can be removed from the ear canal 7 (see Fig. 3). Before the mould 23 is removed from the ear canal 7 the plug 21 is removed from the tube 11 to bring the space between the tympanic membrane 9 and the mould 23 into communication with the outer air, so that no partial vacuum is formed in this space, which may lead to damaging of the tympanic membrane 9. For a satisfactory bonding between the curable material 19 and the tube 11 with the flange 13 the tube and the flange are preferably made of the same material as the curable material, in the present case a silicone compound. The ear mould 23 thus obtained is used to make a moulding die for the manufacture of a custom-made in-the-ear hearing aid. Fig. 4 shows an in-the-ear hearing aid 25 manufactured by the method in accordance with the invention. First a moulding die is made from the ear mould 23. This moulding die is filled with a curable plastics, which adopts the shape of the ear canal 7. After removal of the moulding die the housing 27 of the hearing aid 25 is obtained. In this housing 27 electronic components are mounted, after which the housing is closed by a cap provided with a volume control 31 and a cover 29 giving access to a battery holder. Although the invention has been described above with reference to the drawings it is to be noted that the invention is not limited to the embodiment shown in the drawings. The invention also extends to all embodiments which deviate from that shown in the drawings but within the scope of the Claims and which utilise the basic idea of the invention.

Claims: A method of making an in-the-ear hearing aid (25) for insertion into an ear canal of a person in proximity to a tympanic membrane, which method employs a mould (23) of the ear canal of the person's ear, which mould is used for making a moulding die for the manufacture of a hearing-aid housing, comprising the steps of: inserting an auxiliary tool comprising a flexible tube (11) having an opening at one end and a flange at another end into the ear canal with the flange in the ear canal in order to form the mould, thereafter introducing a curable material (19) into the ear canal and, after the material has cured, removing the material with the tube and the flange from the ear canal, characterized by the steps of: using a flange (13) having an opening (15) situated opposite the opening of the tube (11) so that the tube is open at both ends, bringing the tube with the flange into the proximity of the tympanic membrane in the step of inserting the auxiliary tool such that the step of introducing the curable material (19) presses the flange against the tympanic membrane, thereby precluding the ingress of material between the flange and the tympanic membrane. A method as claimed in Claim 1, characterized in that before the tube (11) is inserted into the ear canal the tube is closed at its end remote from the flange (13), and before the mould (23) is removed from the ear canal the tube is opened at that end. An auxiliary tool comprising a flexible tube (11) having an opening at one end and a flange (13) at another end for making a mould for a housing (27) of an in-the-ear hearing aid (25) and intended for use in the method as claimed in Claim 1 or 2, characterized in that the tube and the flange (13) form an integral unit, the flange having an opening (15) situated opposite the opening of the tube so that the integral unit is open at both ends, and the flange being flexible and thin enough so that, after insertion into the ear canal, the flange conforms to the shape of the tympanic membrane upon introduction of the curable material into the ear canal. An auxiliary tool as claimed in Claim 3, characterized by the presence of a removable plug (21) for closing the opening before the auxiliary tool is inserted into the ear canal.

Inventors: CLAES RUDI ALFONS MARIA, CLAES, RUDI ALFONS MARIA
Applicants: KONINKL PHILIPS ELECTRONICS NV, KONINKLIJKE PHILIPS ELECTRONICS N.V.
Application year: 1992
Main classification: H04R25
IPC codes: H04R25