Note: Descriptions are shown in the official language in which they were submitted.
21~?~0~~
P07'~? WA.E - 1 - 21. Oktober 1994
HEARING AID TO BE WORN IN THE EAR
AND METHOD FOR ITS MANUFACTURE
The invention relates to a hearing aid to be worn in the ear and to a method
for its manufacture according to the preambles of the corresponding
independent claims.
Hearing aids to be worn in the ear normally have a microphone directed
towards the outside of the ear, a loudspeaker directed towards the interior of
the ear, an amplifying electronics and a replaceable battery for operation,
all
said electronic components being located in a shaped member, whose shape is
to a greater or lesser extent adapted to the shape of the auditory canal and
is
worn in the latter. In order that the hearing aid can be comfortably worn and
in order that the hearing aid can fulfil its function in an optimum manner,
various demands are made on the shaped member, which it fulfills to a
greater or lesser extent as a function of the construction. These requirements
are essentially as follows:
- The shaped member must fit well in the auditory canal, so that it has a
good position and is still comfortable.
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- The shaped member must be easily insertable into and removable from
the auditory canal.
- The shaped member must permit a pressure compensation in the auditory
canal, despite its good fit.
S - The shaped member must prevent feedback of the sound produced by the
loudspeaker to the microphone.
- The shaped member must be skin-compatible, must in particular permit a
ventilation of the skin of the auditory canal and must not give rise to the
exudation of perspiration and earwax.
- The shaped member must be insensitive to the exudations of the auditory
canal and easily cleaned with respect thereto and must in particular
protect the electronic components of the hearing aid from such
exudations.
Apart from these requirements relating to the function of the hearing aid and
its wearing comfort, there are economic requirements to the effect that the
shaped member must be easy to manufacture. It could additionally be
desirable for economic reasons for the electronic components to be accessibly
integrated into the hearing aid, so that they can be replaced.
The above requirements are satisfied to a varying extent by known hearing
aids worn in the ear. Some of them will be briefly described and compared
with the above list of requirements.
The most frequently used method for the manufacture of hearing aids to be
worn in the ear comprises a hearing aid advisor, who simultaneously
investigates the hearing weaknesses of the potential user, producing a
silicone
moulding or casting of the auditory canal, on the basis of which is produced a
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P0722WA.E - 3
transparent, positive model of the auditory canal and in said model is
moulded a plastics material polymerizable with the aid of light, which hardens
from the outside to the inside up to a given layer thickness. This leads to a
hollow shaped member, into which the electronic components of the hearing
aid are fitted leaving towards the interior of the ear an opening for the
loudspeaker and for a pressure compensating channel. Against the outlet of
the auditory canal the shaped member is closed with a cover, which contains
an opening for the pressure compensating channel and a separate
compartment for a replaceable battery.
The thus manufactured hearing aid has a shaped member with a very good fit,
but which covers the skin of the auditory canal without interruption in such a
way that there can be no question of a ventilation. This unavoidably leads to
increased exudation of perspiration and earwax. The part of the auditory
canal left free between the eardrum and the hearing aid is open to the outside
through the pressure compensating channel, so that a pressure compensation
can take place and moisture can also escape. However, the pressure
compensating channel can increase the feedback between the loudspeaker and
the microphone.
A further disadvantage of this hearing aid is that the openings to the
loudspeaker and the pressure compensating channel can .become easily
blocked with earwax. For preventing this these openings can also be covered
with a liquid-impermeable, but gas-permeable diaphragm, as proposed in
European patent application 310,866 (published 12.4.1989).
The described hearing aid manufacturing method is complicated, because the
shaped member must be moulded in several positive-negative stages and
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p0722WA.E - 4 -
because the manufacturing stages are such that they cannot be performed by
the hearing aid advisor. Thus, the manufacturer of the hearing aid must deal
with the individual production of user-specific equipment.
In order to simplify the manufacturing methods various proposals have been
made . Thus, e. g. according to US Patent 4,962,537, it is proposed that the
shaped member be in the form of a double-wall bag of a flexible material, a
hardening plastic mass being directly pressed between the two walls when in
the users ear. 'This method saves a few steps in the manufacture, but the
moulded shaped member must still be reworked, in particular it is necessary
to subsequently make openings for a pressure compensating channel and for
the loudspeaker and it is doubtful whether this can be done by the hearing aid
advisor.
The same applies with respect to the hearing aid according to International
patent application W092/03894, whose shaped member is directly moulded in
the auditory canal.
The two aforementioned manufacturing methods are admittedly simpler than
the first-described method, but do not improve the disadvantages with respect
to skin contact and feedback. This also applies with regards to the hearing
aid
of US Patent 4,834,211, in which the shaped member is constituted by a
balloon surrounding the electronic components of the hearing aid and which
during each insertion into the ear is inflated with a corresponding pump. With
such a hearing aid the skin contact and feedback are not improved and there
can be no question of a simple insertion in the ear.
CA 02137098 2004-03-16
The object of an aspect of the present invention is to provide a hearing aid
to be worn
in the ear with a shaped member adapted to an individual auditory canal
(individualized), which hearing aid is manufacturable in a very simple
process, in
particular is individualizable in a very simple process, and which hearing aid
is
$ improved with respect to the wearing comfort compared with known hearing
aids. In
addition, a method is given according to which the hearing aid can be
manufactured
and in particular individualized.
Roughly speaking the method according to the invention is as follows. A
general hearing aid, not yet adapted to an individual auditory canal, is mass
produced. It has an advantageously limitedly plastically deformable skeleton,
which carries the electronic components of the hearing aid and to which is
fixed a flexible diaphragm in such a way that the skeleton and the diaphragm
form a moulding chamber, which is open towards the outside with a pouring
opening. The hearing aid is now individualized (adapted to an individual
auditory canal), in that the skeleton is shaped in accordance with the
individual auditory canal shape, in that the thus partly individualized
hearing
aid is positioned in the ear and then the moulding chamber is filled with a
hardening plastic mass, the diaphragm being deformed and the resulting
shaped member being shaped in accordance with the auditory canal. The
skeleton and diaphragm are constructed and fixed to one another in such a
way that there is no need for any reworking of the hearing aid individualized
by shaping the skeleton and moulding the shaped member.
The material and structure of the diaphragm are such that it is permeable for
gases as a result of an extremely fine porosity, but impermeable for liquids,
in
particular for a liquid or paste-like moulding material, and that it is
sufficiently elastic to be applied in fold-free manner to the auditory canal
wall
on moulding the shaped member. Thanks to the gas permeability of the
CA 02137098 2004-03-16
6
diaphragm there is no need to take any provision for the controlled exit of
the air in
the moulding chamber during pouring (such as provision of a pouring and/or
venting
channel reaching into the moulding chamber or evacuation of the airing chamber
before pouring). Using a gas permeable diaphragm it is sufficient to provide a
pouring
opening onto which e.g. an apparatus for pressing the moulding material into
the
moulding chamber may be fixed tightly.
So that the diaphragm can fulfil its function on a long term basis, it is in
addition
advantageously water and oil-repellent.
As diaphragm, extensible plastic membranes are suitable which by elongation or
perforation through laser, through mechanical means or through plasma etching
are
made porous. Further suitable diaphragm materials are woven and knitted
materials
e.g. from plastic fibers. For an improved wearing comfort the diaphragm may
consist
of a material which is oil and water repellent (e.g. polytetrafluoroethylene)
or the
diaphragm may be coated on at least the surface facing the auditory canal with
an oil
and water-repellent coating. This coating can e.g. be an evaporation coated
coating of
ParylenTM (Union Carbide Corp. USA) or silane.
According to an aspect of the present invention, there is provided a hearing
aid
comprising an outer surface in the shape of an irregular conical frustum and
adapted
to be shaped to the conformation of an individual patient's auditory canal,
the hearing
aid comprising
a skeleton comprising an outer support element forming an outer end face of
the frustum, an inner support element forming an inner end face of the frustum
and a
connecting element interconnecting and maintaining the support elements in
spaced
relationship, the outer support element comprising a pouring opening;
electronic hearing enhancement components carried at least partly by the
skeleton; and
a tubular, microporous, elastic diaphragm comprising a material which is
permeable to gases, impermeable to liquids and is oil repellent, the diaphragm
being
attached at opposite ends to the inner and outer support elements and forming
an outer
CA 02137098 2004-03-16
6a
surface of the frustum;
the support elements, the connecting element and the diaphragm defining an
interior volume within the diaphragm comprising a molding cavity adapted to
receive
a hardenable material through the pouring opening.
According to another aspect of the present invention, there is provided a
hearing aid
comprising an outer surface in the shape of an irregular conical frustum
conforming to
an individual patient's auditory canal and comprising
a skeleton comprising an outer support element forming an outer end face of
the frustum, an inner support element forming an inner end face of the frustum
and a
connecting element connecting the support elements, the outer support element
comprising an opening therethrough;
electronic hearing enhancement components carried at least partly by the
skeleton;
a tubular, microporous, elastic diaphragm comprising a material which is
permeable to gases, impermeable to liquids and is oil repellent, the diaphragm
being
attached at opposite ends to the inner and outer support elements and forming
an outer
surface of the frustum; and
a shaped member molded from a hardenable material and confined within a
volume defined by the support elements, the connecting element and the
diaphragm.
According to a further aspect of the present invention, there is provided a
method of
adapting the exterior shape of a hearing aid to the conformation of a wearer's
auditory
canal comprising
providing a hearing aid comprising a skeleton comprising an outer support
element forming an outer end face of a generally conical frustum, an inner
support
element forming an inner end face of the frustum and a connecting element
connecting the support elements, the outer support element comprising a
pouring
opening, electronic hearing enhancement components carried at least partly by
the
skeleton, and a tubular, microporous, elastic diaphragm comprising a material
which
is permeable to gases, impermeable to liquids and is oil repellent, the
diaphragm
being attached at opposite ends to the inner and outer support elements and
forming
CA 02137098 2004-03-16
6b
an outer surface of the frustum, the support elements, the connecting element
and the
diaphragm defining an interior volume comprising a molding cavity adapted to
receive a hardenable material through the pouring opening;
positioning the hearing aid in the auditory canal of the wearer, and
pressing the hardenable material through the pouring opening into the molding
cavity.
The manufacturing method according to the invention and the hearing aid
manufactured according to this method are described in greater detail
hereinafter
relative to exemplified embodiments and the attached drawings, wherein show:
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P0722WA.E - 7 -
Fig. 1 a diagram of the most important parts of the hearing aid according
to the invention for explaining their functions (section parallel to
the auditory canal axis).
S Fig.2 an exemplified embodiment of the individualized hearing aid
according to the invention in section parallel to the auditory canal
axis.
Figs. 3 and 4 further exemplified embodiments of the hearing aid according to
the invention in the general state (immediately prior to moulding
the shaped member).
Figs. Sa to Sc different methods for manufacturing a diaphragm bag for the
hearing aid according to the invention.
Fig. 1 shows the principle of the hearing aid according to the invention in a
highly diagrammatic manner. The hearing aid is already in its individualized
state and is shown in section parallel to the auditory canal axis. It is
substantially shaped like an irregular frustum with a circumferential surface
M, a larger end face AS directed towards the outside in the auditory canal
and a smaller end face IS directed towards the inside in the auditory canal.
The hearing aid essentially comprises a shaped member 1, whose shape is
adapted to the auditory canal and at least on the circumferential surface M,
i.e. where it contacts the auditory canal wall when the aid is being worn, is
covered with a microporous diaphragm 2. The hearing aid also has a skeleton,
which essentially comprises three parts, namely an outer support element 3,
which essentially forms the outer end face AS of the aid, an inner support
element 4, which essentially forms the inner end face IS of the aid and a
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connecting element 5, which interconnects the two support elements 3 and 4.
The connecting element S serves to keep the two support elements 3 and 4 in
their reciprocal position prior to the moulding of the shaped member and this
roughly corresponds to an auditory canal. The connecting element 5 is
advantageously deformable to a limited extent, so that as a first
individualizing stage the reciprocal position of the support elements 3 and 4
can be adapted to the individual auditory canal.
The outer support element 3 carries a microphone 31 for which it is provided
at the corresponding point with sound passage openings 32. The outer support
element 3 also forms a closable battery compartment 33 and carries a pouring
or injecting opening 34. The inner support element 4 carries a loudspeaker 41
and is also provided with sound passage openings 42.
The microporous diaphragm 2, which surrounds the shaped member at least
on its circumferential surface M, is fixed to the two support elements around
the two end faces AS and IS (points X in the drawing). The diaphragm 2 can
additionally cover entirely the inner end face IS. It can also partly cover
the
outer end face, but must leave freely accessible the pouring or injecting
opening 34 and the battery compartment 33.
The amplifier electronics (not shown) can either be carried by one of the
support elements or by the connecting element. It can also be moulded into
the shaped member without any special fastening to the skeleton.
The skeleton is advantageously made from plastic. The microporous
diaphragm can be fixed to the support elements, e.g. by welding, bonding or
' ' CA 02137098 2004-03-16
-9-
corresponding securing members. Further fastening possibilities will be
described in conjunction with figs. 2 to 4.
The general hearing aid, from which is produced the individualized hearing
aid diagrammatically shown in fig. 1, differs from the latter in that the
shaped
member 1 is only present as a still undefined moulding cavity between the
support elements and the microporous diaphragm. The microporous
diaphragm 2 fixed to the support elements 3 and 4 consequently loosely
surrounds the skeleton and forms with the support elements a moulding
chamber surrounding in tubular manner the skeleton and which is open to the
outside through the pouring opening 34.
The moulding chamber between the diaphragm and the skeleton is filled by a
suitable plastics material (moulding material) through the pouring opening 34,
the hearing aid being positioned in the auditory canal. During moulding the
microporous diaphragm is stretched and positioned without folds on the wall
of the auditory canal. The moulding material hardens to form the
individualized shaped member 1. The requirements made on the moulding
material are that it can easily be poured through the pouring opening and that
it rapidly hardens. For an increased wearing comfort, it is advantageous to
use
a moulding material which is, even in its hardened state, slightly deformable
elastically, such that the shaped member is able to adapt to the changing form
of the auditory canal on e.g. chewing. Obviously the moulding material has to
be skin-compatible.
It has been found that the moulding compound based on vinyl polysiloxane
which is more particularly used in dental technology and which is
manufactured under the name Imprint by 3M is very suitable for the present
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P0722WA.E - 10 -
purposes. This two-component moulding material is obtainable in easily
handlable twin cartridges with cannulas, which can be directly mounted on the
pouring opening 34.
It is obviously also possible to use other moulding materials. Advantageously
use is made of those materials, which do not split off low-molecular weight
radicals during polymerization. Additives, e.g. small foam bodies or hollow
glass balls can be added to the moulding material for improving the
characteristics of the shaped member as a sound and vibration absorber.
The manufacture of the hearing aid diagrammatically shown in fig. 1 e.g.
involves the following stages:
- Produce the skeleton, e.g. by injection moulding of a suitable plastic.
- Install loudspeaker 41, microphone 31 and amplifier electronics on the
skeleton, electrically interconnect them and connect to the battery
compartment 33.
- Surround the skeleton with the microporous diaphragm 2 and fix the
latter to the support elements 3 and 4 (points X).
- Adapt the general hearing aid manufactured in the first three stages
roughly to an individual auditory canal by corresponding deformation of
the skeleton or connecting element 5.
- Position the roughly adapted hearing aid in the auditory canal and
produce the shaped member by filling the moulding chamber between the
diaphragm and the skeleton.
- Insert the battery.
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The stages necessary for individualizing the general hearing aid are the
deformation of the skeleton and the moulding of the shaped member. Both
stages can easily be performed by the hearing aid advisor, in such a way that
the user can take away the hearing aid following one session and the
S manufacturer only has to produce general hearing aids.
The exemplified embodiments of the hearing aid according to the invention
shown in figs. 2 to 4 differ from one another essentially by a pressure
compensating channel, which is or may be absent in the first embodiment, and
in that the electronic components are accessible to a varying extent. The
principle described relative to fig. l is retained in all the embodiments.
Fig. 2 shows a first exemplified embodiment of the hearing aid according to
the invention once again in section parallel to the auditory canal axis. The
aid
is positioned in an auditory canal, the auditory canal walls being indicated
by
the lines G. The represented hearing aid is already individualized. It has a
skeleton, which in turn comprises an outer support element 3, an inner
support element 4 and a connecting element 5 and which carries the
electronic components. This skeleton is located in a moulded shaped member
1, whose surface directed towards the auditory canal is ,covered by a baglike
microporous diaphragm 2.
The two support elements 3 and 4 are constructed as an inner capsule 4.1
with an inner closing element 4.2 and an outer capsule 3.1 with an outer
closing element 3.2, which permit an at least partial accessibility with
respect
to the electronic components on the individualized hearing aid.
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The inner capsule 4.1 houses the loudspeaker 41, which is introduced through
its opening before the closing element 4.2 is engaged thereon. In the outer
capsule 3.1, advantageously in correspondingly arranged compartments, are
housed the microphone 31 in a microphone compartment 31.1 and a battery
in a battery compartment 33. The amplifier electronics 6 can also be housed
in the outer capsule 3.1. The electrical connections between the electronic
components of the hearing aid e.g. run through the deformable connecting
element 5.
The pouring opening 34, which opens the moulding chamber to the outside, is
e.g. shaped onto the outer capsule 3.1. The openings of the individual
compartments of the outer capsule 3.1 and the pouring opening 34 are
substantially located in one plane, so that they can be jointly closed by the
closing element 3.2. However, it is also possible to provide separate closing
elements for the different openings or for certain of the openings to design
partial areas of the common closing element 3.2 in such a way that they can
be opened and closed, without having to open the entire closing element 3.2.
In fig. 2 the battery compartment 33 is closed with such a partial closing
element 33.1 and is therefore very readily accessible to the user.
The bag-like microporous diaphragm 2 has a main opening, whose edge is so
fixed around the area in which are located the opening of the outer capsule
3.1 and the pouring opening 34, that the entire skeleton except for the
pouring opening 34 and the opening of the outer capsule 3.1 is embraced by
the diaphragm 2. The fixing of the microporous diaphragm 2 around the outer
capsule is brought about by an outer diaphragm fixing means, which can e.g.
comprise a fixing ring 10 positively arranged around the outer capsule (on the
left-hand side of the drawing) or by a corresponding positive design of the
marginal areas of the closing element 3.2 (on the right-hand side of the
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P0722WA.E - 13 -
drawing). If the microporous diaphragm 2 is fixed by the closing element 3.2
to the outer capsule 3.1, the closing element 3.2 must have for the pouring
opening 34 a removable partial area (in the manner shown in the drawing for
the battery compartment 33) or at least an opening.
Around the opening of the inner capsule 4.1 the microporous diaphragm 2 is
fixed with an inner diaphragm fixing means and, as shown, covers the
loudspeaker opening or can have in said area a further opening. The inner
diaphragm fixing means is e.g. the perforated, inner closing element 4.2
positively fitting onto the opening of the inner capsule 4.1 which secures the
diaphragm 2 around the opening of the capsule 4.1 in such a way that the
moulding material cannot enter the opening, which in use mechanically
protects part 21 of the diaphragm 2 covering the capsule opening
mechanically and which does not constitute an obstacle for the sound of the
loudspeaker (sound passage openings).
That part of the opening of the outer capsule 3.1 located above the
microphone compartment 31.1 can also be covered with a diaphragm. As
shown in fig. 2, it can be in the form of a separate diaphragm portion 22
secured between the closing element 4.2 and the capsule wall, or in such a
way that the diaphragm 2 engages in one piece over the said opening and is
held in the same way as on the opening of the inner capsule 3.1. The closing
element 3.2 is advantageously perforated in the area covering the microphone
compartment 3.1.
As stated already, the diaphragm 2 can also be welded or bonded to the
capsules or the corresponding closing elements.
CA 02137098 2004-03-16
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The embodiment of the inventive hearing aid according to fig. 2 does not
have a pressure compensating channel. However, as a pressure compensation
between the innermost part of the auditory canal closed by the hearing aid
and the outside is necessary, the embodiment must have a microporous
diaphragm which is gas permeable not only from main surface to main surface
but also parallel to these main surfaces (laterally).
It has been found that a foamed and stretched PTFE diaphragm
manufactured under the name GORE-TEX~by W.L. Gore & Co. GmbH
(D-88011 Putzbrunn near Munich) has the necessary characteristic and is
suitable for use. It is a foamed and stretched P'TFE material (polyte-
trafluoroethylene), which forms a very fine porous diaphragm. This diaphragm
not only has the necessary physical characteristics, but is also very friendly
to
the skin and body (it can be used as a provisional skin in the case of
large-surface wounds).
The GORE-TEX diaphragm is not only gas-permeable at right angles to its
surfaces, but also parallel t>;ereto, so that not only can the air displaced
during moulding escape through this diaphragm, but it can also serve as a
pressure compensating means and for ventilating the auditory canal skin. This
effect can be improved in that the diaphragm bas on its side facing the
skeleton a coarse, porous intermediate layer, which can be a layer of an .
open-pore foam or a gauze.
During the moulding process and particularly during its final phases when the
shaped member already firmly engages on the auditory canal, a pressure
compensation takes place through the diaphragm and the intermediate layer,
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P0722WA.E - 15 -
if provided, parallel to the main faces thereof, so that no pressure can build
up through the moulding in the auditory canal closed by the shaped member.
Figs. 3 and 4 show another embodiment of the hearing aid according to the
invention. 'The principle once again corresponds to that described in
conjunction with fig. 1 and the main components of the hearing aid also
correspond thereto, so that there is no need to give another description
thereof. The difference compared with the hearing aids of figs. 1 and 2 is
that
the connecting element 5 is hollow and serves as a pressure compensating
channel, issuing openings 45 and 35 being provided in the inner support
element 4 and the outer support element 3. The pouring opening 34 is
arranged in the battery compartment 33. The inner end face IS is covered
with a separate diaphragm portion 46, the area of the microphone 31 and the
outer issuing opening 45 of the pressure compensating channel also being
covered with a separate diaphragm portion 36. The moulding compound is
moulded directly around the microphone 31 and the loudspeaker 41 or they
can be surrounded on the shaped member side with a sound insulating
material 37.
For the embodiment of the inventive hearing aid according to Figs. 3 and 4,
which has a pressure compensating channel, it is sufficient, when the
microporous diaphragm is gas permeable between its two main faces. The gas
permeability in this case is used only for venting the moulding chamber during
moulding, whilst the aeration and pressure compensation of the closed part of
the auditory canal is taken over by the pressure compensation channel. Such
microporous diaphragms are made e.g. from silicone polymers cross-linked by
addition or condensation, e.g. from Vinylpolysiloxane, or from other plastic
materials. Such originally gas tight membranes are extensible up to 200% and
are made porous by laser, by plasma etching or by mechanical means before
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P0722WA.E - 16 -
being formed into a bag. The pores have a diameter of SO~.m maximum and it
shows that 10 to 20 pores per diaphragm bag are sufficient. As stated before
the porous diaphragm can be made oil and water-repellent e.g by coating it in
a fluorine containing plasma.
Fig. 3 shows the hearing aid in the general state as supplied by the
manufacturer.
Fig. 4 shows the hearing aid in the auditory canal G ready for moulding. In
order to keep the pouring opening 34 free, the battery and battery
compartment cover are removed. In order to free the issuing openings 35 and
45 of the pressure compensating channel, the separate diaphragm portions 36
and 46 (fig. 3) are removed and to the inner end face IS of the hearing aid is
fitted a protective element, secured with a wire 7 through the pressure
compensating channel and which not only protects the eardrum during
moulding, but is also intended to assist the positioning of the not yet
individualized hearing aid in the auditory canal. The protective element 48 is
e.g. made from foam. The wire 7 carrying the protective element can
additionally serve as an aid for the insertion of the hearing aid into the
auditory canal and for the removal thereof.
Prior to moulding, i.e. in the general state of the hearing aid, the
microporous
diaphragm must akeady have a shape roughly corresponding to the auditory
canal, so that it surrounds in fold-free manner the shaped member in the
individualized state of the hearing aid. In particular it must be fixable with
the
minimum of folds or creases around its main opening (outer end face) and
round the opening on the inner end face. For this purpose the diaphragm
must be present in the form of a bag tapering away from the main opening.
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P0722WAE - 17 -
Such a diaphragm bag can be produced in numerous different ways, as shown
in figs. Sa to Sc.
In the case of adequate diaphragm deformability such a bag S, as shown in
fig. Sa, can be drawn from a flat portion ME of a diaphragm. This production
procedure requires an adequate deformability of the diaphragm, but is
advantageous if the inner end face of the hearing aid is to be covered by the
diaphragm, i.e. if the diaphragm bag is only to have a main opening, but no
further opening.
Fig. Sb shows a method for the manufacture of a diaphragm bag S from a flat
diaphragm portion ME, from which has been cut a piece K in the form of a
developed frustum jacket. This piece K is formed into the diaphragm bag S
with a main opening H and a further opening W, e.g. by welding.
Fig. Sc shows the manufacture of a diaphragm bag with a main opening H
and a further opening W from a piece of diaphragm hose MS by widening its
one end to a larger diameter.
In order to assist the gas exchange in the direction of the main faces of the
diaphragm it is possible, as stated, to draw it onto a second layer
(intermediate layer), which is located between the diaphragm and the shaped
member on the finished hearing aid, i.e. does not come into contact with the
skin of the auditory canal. As stated, said layer can be an open-pore foam or
a gauze onto which the diaphragm is drawn. It has been found that such an
intermediate layer can also facilitate the manufacture of the diaphragm bag.
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P0722WA.E - 18 -
Figs. 1 to 4 show hearing aids of which the narrower end is worn in the
auditory canal while the wider end is positioned in the external ear. It is
therefore a so called ITC hearing aid (in the canal). Obviously the inventive
hearing aid is adaptable also to be a CIC hearing aid (completely in the
canal), which is a hearing aid with a more cylindrical form which is fully
inserted into the auditory canal
