Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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ELECTRIC/ACOUSTIC TRANSDUCER MODULE, INTRA-AURAL HEARING-AID
AND METHOD FOR PRODUCING AN INTRA-AURAL HEARING AID
The present invention relates to an electric/acoustic transducer
module for behind-the-ear or in-the-ear hearing aids and a manufacturing
method
for such an in-the-ear hearing aid.
In the case of hearing aids and, in particular,
in-the-ear hearing aids, it is important that the
loudspeaker housing is not connected to the auditory
canal by a mechanically rigid bridge. This is
important to prevent acoustic feedback from the
loudspeaker to the input-side microphone as far as
possible. Furthermore, where hearing aids are
concerned, the space available is generally extremely
limited and must be used optimally.
EP 0 548 580 discloses, for example, providing
the electric/acoustic transducer arrangement on an in-
the-ear hearing aid with a loudspeaker housing in which
the motor-driven loudspeaker diaphragm and the motor
driver for it are mounted. The diaphragm or the motor
drivers for it are mounted in relation to said
loudspeaker housing in such a way that the signals
induced acoustically by the diaphragm are transmitted
directly to said housing. Said arrangement is fitted
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in an in-the-ear hearing-aid housing in such a way that
the loudspeaker housing is as far away as possible from
said hearing-aid housing, whereby only reduced acoustic
transmission bridges are formed. As a result, however,
assembly of the hitherto known hearing aids demands
meticulous care that such bridges are not formed, i.e.
a transducer arrangement must be inserted manually in
the hearing-aid housing, as is also the customary
practice, and meticulously aligned there.
According to the present invention, there is provided a transducer
arrangement with a size enabling integration into a hearing aid device and
comprising:
an encapsulation with an opening;
a transducer housing resiliently mounted in said encapsulation and defining
an intermediate space between said transducer housing and said encapsulation;
a first membrane in said transducer housing having a first side and a second
side;
a second membrane closing said opening;
a first space adjacent to said first side of said membrane and communicating
with said opening;
a second space adjacent to said second side of said first membrane and
communicating with said intermediate space, wherein
said transducer forms a self-contained module with said encapsulation as a
housing of said module and defines a predetermined volume of said intermediate
space, and wherein
said module is adapted for insertion into an additional space formed by a
device housing of the hearing device.
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Preferably, because the loudspeaker housing is resiliently mounted in
the enclosure, it is possible for the transducer module to be installed in a
behind-
the-ear or in-the-ear hearing aid, whether in a form-fitting or frictionally
locking
manner. Furthermore, the, as mentioned, already necessary intermediate space
between the loudspeaker housing and the hearing-aid housing is now exploited
to
acoustically improve the behaviour of the hearing aid. This is achieved by the
intermediate space provided by the invention at the transducer itself raising
the
bass range of the transducer module
i'
/
/
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by several dB, in that the intermediate space created
by the invention en:larges by a multiple the chamber
acoustically effective at the rear of the diaphragm as
compared with this rear chamber in the loudspeaker
housing itself. Reference can be made in this respect
to US-A-3 257 516, where the advantages of large rear
chambers are presented.
In a preferred embodiment, the enclosure acts
as a magnetic shield and, for this purpose, is
preferably made of metal. Very simple assembly and
disassembly of the transducer arrangement, in
particular the insertion of the loudspeaker housing
with loudspeaker, is achieved by the enclosure
comprising a cup-shaped part. This is preferably
metallic. In a further preferred embodiment, -
following insertion of the loudspeaker housing with
loudspeaker - said ciap-shaped part is closed by means
of a cover element which has the acoustic output of the
transducer arrangement. In an embodiment preferred by
far, said cover element comprises as the acoustic
output an aperture at which the first chamber on one
side of the loudspeaker diaphragm, that is to say that
chamber which is coupled to the acoustic output of the
transducer arrangement, is separated from the ambience
by means of a memb:rane. The membrane lies in an
unhampered manner across the aperture. In a further
embodiment, the cup is completed by a hose-like
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elastomeric cover. Both designs practically achieve a
sealing of the interior of the transducer module, which
is highly desirable in view of the soiling of
acoustically importarat t'ransmission elements, known in
particular in the case of in-the-ear hearing aids.
Consequently, it is readily possible to clean the
transducer module with respect to soiling of this kind.
Neither dirt nor moisture can enter the module.
The membrane provided according to the
invention in the preferred embodiment mentioned differs
from that presented and described for example in the
aforementioned EP 0 548 580 by being installed in a
freely vibrating manner and not motor-driven. By
dimensioning the acoustically effective chambers
provided according to the invention and the membrane
characteristics in a way customary to a person skilled
in the art, with impedance matching in mind, the effect
is achieved that said membrane scarcely affects the
acoustic transmission behavior of the hearing aid on
the output side of the loudspeaker.
In a particularly preferred embodiment, at
least the free part of the membrane is in this case
made homogeneously in. terms of its material, i.e. from
one material phase, and, in a further preferred
feature, is of a constant thickness. Consequently,
said membrane is of an extremely simple structural
design and the acoustic behavior of the membrane is
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straightforward.
In a preferred embodiment, at least the free
part of said membrane is in this case of elastomeric
material, such as for example latex or silicone rubber,
extremely low-cost materials that are produced with a
uniform, small thickness, resistant and unobjectionable
with respect to how they behave in contact with living
tissue. The membrane is preferably airtight. Its
thickness is preferably d<_ 0.09 mm.
Furthermore, to allow the loudspeaker housing
to be installed as simply as possible into the
enclosure while taking into account the acoustic
decoupling between the loudspeaker housing and the
enclosure,it is preferably proposed that the loudspeaker
housing is fixed in the enclosure by means of flexible
bearing blocks. Furthermore, to optimally exploit said
intermediate space, it is further proposed in a
preferred embodiment that the loudspeaker housing is
enclosed on all sides by said intermediate space apart
from bearing locations of the loudspeaker housing on
the enclosure.
The in-the-ear hearing aid according to the
invention has an electric/acoustic transducer
arrangement of the type described above. The potential
for simple assembly is fully exploited in that the
enclosure of the transducer module is positioned in the
hearing-aid housing in a form-fitting and/or
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frictionally locking manner.
As a result, and as still to be mentioned, this
creates the basis for producing such hearing aids in an
automated manner: the avoidance of acoustic bridges
between the loudspeaker housing and the housing of the
hearing aid is solved a priori by installing the
transducer module according to the invention.
At the same time, in a preferred embodiment of
the hearing aid according to the invention, the
acoustic output of the transducer module can be
connected to the acoustic output aperture of the
hearing-aid housing, again in a customary way, by means
of a tubular stub.
In a further preferred embodiment of the in-
the-ear hearing aid according to the invention, in any
event a membrane fixed in such a way as to allow free,
unhampered vibration is provided, separating the
ambience of the hearing aid from the first chamber at
the transducer module used according to the invention.
This membrane may obviously be formed by the
previously mentioned membrane on the transducer
arrangement accordinc; to the invention itself, though
this is not mandatory and the preferred embodiments
[sic] made in this respect above apply in all cases.
In a further preferred embodiment, however, said
membrane is mounted directly in the region of the
acoustic output of the hearing aid. This prevents any
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soiling at all from entering not only the transducer
module but also the transducer input at the hearing aid
itself.
In a further preferred embodiment of the
hearing aid according to the invention, the acoustic
output of the transducer module according to the
invention is therefore provided essentially directly at
the output aperture af the hearing-aid housing, whereby
said membrane, if provided in the preferred way, is
provided directly in the ambience of the hearing-aid
housing on the one hand and directly at the output of
the transducer module on the other hand. As a result -
as mentioned - on the one hand this solves the problem
concerning the trapping of dirt at an output aperture
provided at the hearing aid by said aperture being
closed directly by said membrane, on the other hand it
provides the possibility of optimizing the acoustic
behavior in the sense that no additional intermediate
transmission paths have to be provided from the
acoustic output of the transducer module to the
acoustic output of the hearing aid. The remaining
acoustic transmission path can be provided solely on
the basis of acoustic impedance matching.
In an embodiment of the hearing aid most
especially preferred in terms of design, the acoustic
output aperture of the hearing-aid housing is formed by
an element connected in a plate-like manner to the
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remaining hearing-aid housing, for example welded or
adhesively bonded. It is preferably proposed in the
case of this embodiment as well that said output
aperture is closed by means of a membrane, which
however is now preferably formed integrally with said
element. The comments mentioned above also apply with
respect to this membrane, which means that said element
preferably consists of elastomeric material, for
example of latex or silicone rubber.
Preferably, the method according to the invention for
manufacturing a hearing aid, in particular an in-the-ear hearing aid according
to the invention, is distinguished by the fact that the transducer module is
positioned in the hearing-aid housing in a form-fitting or frictionally
locking
manner. This makes it possible with little effort for the transducer module to
be
positioned in the hearing-aid housing exactly in place or even to be pressed
in
a frictionally locking manner between elements of the hearing-aid housing or,
for example, for the transducer module to be cast with the hearing-aid
housing.
As a result, the preferred embodiment of said
method is made possible, that is of inserting the
transducer module into the hearing-aid housing in an
automated manner.
In a further preferred embodiment, the
transducer module is then inserted into the hearing-aid
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housing through an aperture forming the acoustic output
of the hearing-aid housing, that is to say from below.
This provides the basis for a further preferred
approach, that is that the transducer module is
positioned into a receiving aperture of a support plate
and, by means of relative movement of the support plate
and the hearing-aid housing, the transducer module is
inserted into the hearing-aid housing from the end
forming the acoustic output of the hearing-aid housing.
The automation procedure made feasible in this way is
quite clear to a:person skilled in the art: the
appropriate number of' transducer modules are positioned
into a multiplicity of receiving apertures in said
support plate and said modules are pushed from below
into a corresponding number of hearing-aid housings of
in-the-ear hearing aids to be manufactured.
In a further preferred embodiment, the support
plate is subsequently used as part of the hearing-aid
housing by being connected to the hearing-aid housing,
preferably adhesively bonded or welded, and then the
support plate is trirnmed off along the outside contour
of the hearing-aid housing.
In a further preferred embodiment of the method
according to the invention, the receiving aperture for
the transducer module on the support plate is formed as
a blind aperture, providing the possibility, in a
further preferred embodiment, of forming the base
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element of the blind aperture as the abovementioned
membrane, integrally with the support plate, or mounted
on the support plate as a sheet-like structure. If the
cover of the blind aperture is used as a membrane in
the sense referred to above and is integral with the
support plate, the support plate will, as is clearly
evident, be produced from material which meets the
requirements for the material of the membrane, that is
to say preferably from elastomeric material, in this
case for example front latex or silicone rubber.
The invention is explained below by way of
example on the basis of figures, in which:
figure 1 shows the diagram of a transducer
module according to the invention;
figure 2 shows in a diagrammatically
simplifying form a longitudinal section through a
transducer module according to the invention;
figure 2a shows a diagrammatic representation
of a further preferred embodiment of the transducer
module according to the invention;
figure 3 shows, again diagrammatically, the
installation of a transducer module according to the
invention on an in-the-ear hearing aid;
figure 4 shovvs in a representation analogous to
that of figure 3 a further possible way of installing a
transducer module according to the invention on an in-
the-ear hearing aid;
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figure 5 shows in a representation analogous to
Figures 3 and 4a further preferred design variant of
the element forming the acoustic hearing-aid output of
an in-the-ear hearing aid, and
figures 6(a) to 6(c) diagrammatically show the
sequence of a manufacturing method for an in-the-ear
hearing aid with regard to assembling the
electric/acoustic transducer module and the hearing-aid
housing.
Figure 1 diagrammatically shows a transducer
module for explaining the acoustic coupling principles.
The transducer module 1 comprises a loudspeaker
housing 3, in which the loudspeaker diaphragm 5 is
mounted. The loudspeaker diaphragm 5 is excited by a
motor drive 7, which is only diagrammatically
represented. In the loudspeaker housing 3, a front
chamber Rl and a rear chamber R2 are formed by the
loudspeaker diaphragm. 5. One of the two said chambers,
for example the rear chamber R2, is acoustically coupled
by acoustic couplinci apertures 9 to an intermediate
space 11, formed between the loudspeaker housing 3 and
an enclosure 13. The enclosure 13, and consequently
the intermediate space 11, surround the loudspeaker
housing 3 essentially entirely, apart from resilient
bearing elements 15, by means of which the loudspeaker
housing is kept at a distance, mounted essentially in a
floating"_ manner, within the enclosure 13. According
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to figure 1, the front chamber R1 is connected to the
acoustic output AA of the transducer module 1.
With the design shown; an acoustic decoupling
of the effect of the loudspeaker on the enclosure 13 is
achieved on account of the essentially floating
mounting of the loudspeaker housing 3. Furthermore, by
significantly enlarging the rear diaphragm chamber R2,
that is including the intermediate space 11, the
acoustic behavior of the transducer module 1 is
significantly improved as compared with that of the
loudspeaker arrangement in the housing 3: the bass
response of the transducer module is raised by several
dB as compared with the bass response of the
loudspeaker arrangement in the housing 3.
In a preferred embodiment of the transducer
module 1, a membrane is provided at the acoustic output
AA of this module itself, as diagrammatically
represented by 17. Apart from being fixed at its edge,
the membrane 17 vibrates freely. It preferably
consists of a homogeneous material phase, preferably an
elastomeric material, for example latex or silicone
rubber, and, in a further preferred feature, has a
constant thickness of about 100 m, preferably at most
0.09 mm.
By matching the acoustic impedance of the
intermediate space 11, with the chamber Rz, the chamber
R1 as.far_as the membrane 17, the membrane 17 and any
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acoustic conductor that might be provided to propagate
toward the ambience U' of the transducer module 1, the
effect is achieved that the membrane 17 is practically
acoustically transparent.'
Figure 2 shows a cross section through an
embodiment of the transducer module 1. The reference
symbols already used in the diagrammatic representation
of figure 1 are also used here. The loudspeaker
housing 3 with the coupling apertures 9 is mounted on
the enclosure 13 by nteans of elastomeric bearing blocks
19. The enclosure 13 is formed by a cup 20, which
preferably acts at t:he same time as a magnetic shield
and, for this purpose, preferably consists of metal.
In any event, the cup 20 is preferably metallic. The
cup 20 is closed by a cover part 22. The membrane 17,
already presented in figure 1, may in this case be
mounted directly on the cover part 22. At the same
time, the cover part 22 and the membrane 17 may well be
integrally formed, in which case however the material
of the cover part 22 must meet the material
requirements for the membrane, for instance with
respect to elastomeric behavior. For example, the
entire part 22 is then made of latex or silicone
rubber. Otherwise, however, the membrane 17 is
anchored as a separate part on the cover part 22. The
membrane 17 may also be provided between the acoustic
output A3_in the loudspeaker housing 3 and the clear
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aperture in the part 22. Preferably, however, as
represented in figure 2, the membrane 17 is provided
flush with the clear aperture in the cover part 22,
whereby the complete transducer module 1 appears as a
self-contained, enca:psulated unit and can be readily
cleaned. This is especially significant if, as still
to be shown, the output AA of the transducer module 1
lies directly at the acoustic output of a hearing aid.
The transducer module or its enclosure 13 may
be cubic, cylindrical. or designed in some other form of
essentially any desired kind, provided that the
required intermediat(=_ space 11, essentially enclosing
the loudspeaker housing 3, is formed between the
loudspeaker housing 3 and the enclosure 13. On the
basis of the explanations relating to figure 2, figure
2a shows a further embodiment in a merely diagrammatic
form. Here, an elastomeric hose 17a is pulled over the
enclosure 13. Said l:iose 17 at the same time forms the
cover part 22 and membrane 17.
Figure 3 diagrammatically shows the segment of
an in-the-ear hearing aid 24 with the acoustic output
aperture A24. The transducer module 1, designed as
shown in figures 1, 2 and 2a, is installed within the
hearing-aid housing 26, to be precise in that it is
secured and positioned in the housing 26 of the hearing
aid in a form-fitting or frictionally locking manner,
as diagrammatically represented by the securing and
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positioning clips 28 in figure 3. This is made
possible by the acoustic decoupling of the outer
enclosure 13 with respect to the loudspeaker housing 3
provided on the transducer module explained with
reference to figures 1, 2 and 2a.
Apart from this, the design of the in-the-ear
hearing aid shown in figure 3 is essentially as already
known, in that the acoustic output of the transducer
module 1 is connected to the acoustic output aperture
A24 of the hearing aid via an tubular stub 30.
The electronic components and the input-side
acoustic/electric transducer arrangement on the in-the-
ear hearing aid 24 with the housing 26 are not
represented in figure 3 and the further figures because
they are not essential for the invention.
As figure 3 further shows, the membrane 17
provided in the preferred embodiment is installed in
the direct region of the acoustic output A24 on the
hearing-aid housing 26.
According to figure 4, the transducer module 1
is fitted in a form-fitting or frictionally locking
manner directly in the region of the acoustic output A24
of the hearing aid 24 or of the housing 26, as
represented by the diagrammatically shown securing
means 28a. In a;preferred embodiment, the freely
vibrating membrane 17 is provided at the end.
According to figure 5, the housing 26 of the
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in-the-ear hearing aid 24 is formed on the one hand by
a main housing part 24a, but at the end a cover part
24b is placed in a plate-like manner on the part 24a,
glued or welded to the part 24a. A transducer module 1
as described in relation to figures 1 and 2, or
directly the loudspeaker housing of a hitherto known
loudspeaker arrangement, in figure 5 both denoted
together by 30, is seated in the output aperture 32 of
the cover part 24b and is secured there, such as by
clamping, gluing et.c. If the transducer module
represented in a general manner by 30 in figure 5 is
one with an enclosuri=_, i.e. is designed in the manner
of figures 1, 2 or 2a, positioning and fixing members
may be provided for this transducer module 1 within the
hearing-aid housing 26, as in turn diagrammatically
indicated by 28.
The membrane of the type described above, or a
preferably provided membrane, is also represented by 17
in figure 5, in a preferred position. As still to
become evident, the design according to figure 5 has
major advantages, whether for hearing aids with a
transducer module according to figures 1, 2, 2a or for
hearing aids with a hitherto known transducer
arrangement, i.e. with a loudspeaker housing directly
on the outside. Furthermore, the membrane 17 may be
integrally formed with the part 24b, in particular
because, with the part 24b separate from the rest of
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the housing 26, the choice of material for this part
can be matched to the: requirements of the membrane 17.
Figures 6(a) to 6(c) diagrammatically show the
sequence of a preferred' manufacturing method for in-
the-ear hearing aids.
According to figure 6(a), receiving apertures
36, preferably in the form of blind apertures, are
provided in a support plate 34 and the transducer
arrangements 30 to be provided on in-the-ear hearing
aids are inserted in said apertures. If the transducer
arrangements 30 are of a known type, i.e. with an
external loudspeaker housing and without an enclosure
according to figur=es 1, 2, 2a, the transducer
arrangements 30 are preferably firmly anchored in the
support plate 34, for instance are adhesively bonded to
it. If, however, they are transducer arrangements with
an external enclosure according to figures 1, 2, 2a,
the arrangements 30 need not be firmly secured in the
support plate 34, because they can, as has been shown,
be secured in the corresponding hearing-aid housings
24a in a form-fitting or frictionally locking manner,
as indicated with dashed lines by 28b. Of significance
with regard to the technical aspects of the method is
firstly that, due to relative movement of the plate 34
with the transducer arrangements 30 and a corresponding
number of housing parts 24a, the transducer
arrangements 30 are not pushed in the customary manner
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from above, but from below, into the elements of the
housing parts 24a facing the acoustic output.
In the case in ' which the transducer
arrangements 30 are designed with enclosures, once the
transducer systems 30 have been pushed into the
housings 26 in a securing manner, the support plate 34
can be removed, the transducer arrangements or modules
being secured and positioned in the housings 24a.
However, in the case concerning transducer arrangements
without enclosures, the transducers 30 remain in the
apertures 36 of the plate 34 provided for them. The
plate 34 is connected, for example adhesively bonded or
welded, to the housing 24a and, based on the position
according to figure 6(b), the plate 34 is subsequently
trimmed to become flush with the outer housing contour
(transition to figure 6(c)).
This produces the in-the-ear hearing aid as
represented in figure S. However, this procedure is
also used with preference for transducer modules
designed according t.o figures 1, 2, 2a, i.e. with
enclosures.
It is thus evident from viewing figure 6 that
this procedure is extremely well-suited for installing
the membrane 17, or a further membrane preferably to be
provided, at the same time as a guard to protect the
acoustic hearing-aid output from soiling and to ensure
simple cleaning. For this purpose, the base plate 38
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according to figure 6(a) of the preferred apertures 36,
preferably formed as blind apertures, is formed
directly as the membrane. This takes place by either
the material of the support plate 34 being chosen to
meet the requirements for the membrane material, and
consequently the membrane being formed integrally with
the plate 34, or, as represented by dashed lines in
figure 6(a), by the blind apertures 36 being formed by
laminating the support plate 34, the apertures 36 still
being open right through, with a sheet-like layer 34b
which then forms the membrane 17 according to figure 5.
The production method represented makes it
possible to fit both transducer modules according to
figures 1, 2, 2a and conventional transducer
arrangements, i.e. with an external loudspeaker
housing, in the in-the-ear hearing-aid housing without
meticulous positioning manipulations. This can be
carried out from that. side of the housing on which the
acoustic output lies. Consequently, assembling of a
kind which can be automated to the greatest extent is
made possible. If, as preferred, the acoustic output
of the hearing aid is to be designed such that it is
protected against soiling from the ambience and allows
good cleaning, this at the same time provides the
possibility, as explained, of also installing a
covering membrane 17.
