Abstract:
A hearing device includes a BTE unit and a thin acoustic tube. The BTE unit includes a microphone, an amplifier, a power source, and a receiver and is configured to mount behind or on a user&#39;s ear. The tube includes a proximal end and a distal end with the proximal end and the distal end being connected to the receiver and to a flexible mounting insert respectively. The insert comprises a dome shape part and at least one core hole permeable for sound transmitted from the tube, which is configured to arrange in a user&#39;s ear canal to transmit sound generated by the BTE unit to a tympanic membrane of the user. The inserts diameter is adapted to at least have the same diameter as user&#39;s ear canal diameter to close the ear canal of the user and has at least one internal vent pathway located on the circumference of the core hole.

Description:
FIELD OF THE INVENTION 
     The present invention concerns a hearing device comprising a BTE (Behind-The-Ear) unit, which is adapted to be mounted behind or on the ear of a user and further comprising a thin acoustic tube connected to a flexible mounting insert, which comprises a dome shape part and at least one hole for venting. 
     DESCRIPTION OF RELATED ART 
     Hearing devices are generally characterized by the way they are fitted to the ear of a user. The BTE type hearing device is mounted behind or on the ear of a user and comprises a BTE unit and a thin tube, where the BTE unit comprises a microphone, an amplifier, a power source and a receiver (speaker). The BTE unit is connected to the thin tube with a distal end of the tube fitted in the ear canal of a user, which transmits sound from the BTE unit or a speaker unit (receiver unit) at the end of the thin tube to the tympanic membrane in the ear canal of the user. A description on various other types of hearing devices can for example be found in US 2008/0123889 A1 and references therein. 
     Hearing devices generally suffer from various acoustic effects, e.g. the interference of hearing device generated sound and natural sound reaching the tympanic membrane of a hearing device user or direct acoustic feedback, which is a consequence of hearing device generated sound to be reflected from the walls of the ear canal to the microphone of the hearing device leading to sound oscillations. These effects can be suppressed by closing the ear canal of a hearing device user, which effectively prevents natural sound to reach the tympanic membrane and hearing device generated sound to reach the microphone of the hearing device. Closing the ear canal, however, generates an occlusion effect, which corresponds to the amplification of a person&#39;s own voice when the person&#39;s ear canal is blocked. The amplification in the occlusion effect is a result of reverberating bone-conducted sound vibrations off the object/hearing device filling the ear canal towards the tympanic membrane, as the vibrations cannot escape through the ear canal. 
     To prevent the occlusion effect a known technique is to introduce a hole for venting in the hearing device part that fills the ear canal. The common vent design is made by adding a vent hole through a dome, which is connected or part of the hearing device with the vent hole diameter and its length having a large impact on the direct acoustic feedback and the occlusion effect. 
     A common dome is produced by addition of a hot fluidic material into tooling forms, which forms a dome through a hardening process. This method limits the design freedom of the dome, as the holes for sound transmission and venting have to be formed through long and thin tooling forms which are vulnerable due to their high length and small diameter. 
     Another problem regarding vent holes or small holes in general is the risk of occlusion with ear wax, which can change or remove the effect of the vent or reduce the transmission of sound, as the vent and the core hole for the sound transmission can be filled with ear wax. Further the introduction of a vent hole requires extra material, as the hole needs a canal with a certain length to function properly, otherwise the hole is likely to be closed due to squeezing of the dome in the ear canal, which limits the smallest possible dome size. 
     JP 8-37697 (A) presents an earplug comprising an earplug main body and a connection member. The earplug main body comprises a base hole that can be used as a vent. The connection member contains four through-holes at a flange part. If the earplug main body and the connection member are connected and their holes are not aligned the earplug is turned to a state where no vent is formed. A vent can be attained if one of the through holes of the flange part is aligned to the base hole of the earplug main body. 
     In US 2008/0226114 A1 an adapter for use with sound devices is presented. The adapter includes an adapter body with a projection extending from a wall of the adapter body. A sleeve that extends into an ear canal of a user is attached to the projection. The adapter body includes one or more orifices extending through the wag of the adapter. The Sleeve may include a thin layer of a sound transmitting material or scrim. 
     US 2008/0123889 A1 shows a hearing aid device adapted for use within the ear canal of CIC (Completely-In-The-Canal) and of the partially exposed ITC (In-The-Canal) type. The hearing aid device consists of a system of integrated parts that allow air passages to communicate with the inner ear while the aid is in the ear canal. The hearing aid case is smaller than the wearer&#39;s ear canal to form an open passageway between the case and the ear canal. A flexible mounting insert comprises openings to create a sound path extending from the tip of the hearing aid device through the open passageway. 
     US 2010/098281 A1 presents a multi seal system for retaining a hearing device within a bony portion of an ear canal comprising at least two seals with one having a curved shell with an opening at the apex portion of the shell. A vent can be positioned near or in the opening. The shell has an interior surface wall with scalloped shape to support the shell in conforming to the ear canal and to maintain an acoustical seal in this way. The first seal can center a first device component at a first location in the ear canal and the second seal can center a second device component at a second location in the ear canal. 
     WO 99/07182 A2 presents an acoustic coupler detachably secured to a receiver assembly for deep insertion into an ear canal. The acoustic coupler provides a semi-rigid, thin walled, cylindrical coupling sleeve adapted to be attached over the cylindrical receiver assembly. A conforming sealing material is attached to the coupling sleeve, which is used to seal the ear canal acoustically. The sealing material can include a venting pathway. A ball joint can allow the receiver assembly to achieve articulation. A lubricous coating or a coating with medicinal properties can be applied on the sealing material. The receiver assembly can comprise a debris guard. 
     The present invention provides an improved hearing device. 
     SUMMARY OF THE INVENTION 
     The present invention provides a hearing device comprising a BTE (Behind-The-Ear) unit and a thin acoustic tube. The BTE unit comprises a microphone, an amplifier, a power source and a receiver (speaker) and is configured to be mounted behind or on the ear of a user. The thin acoustic tube has a proximal end and a distal end. The proximal end of the thin acoustic tube is connected to the receiver of the BTE unit and the distal end is connected to a flexible mounting insert. The flexible mounting insert comprises a dome shape part and at least one core hole permeable for sound transmitted from the thin acoustic tube. The thin acoustic tube is configured to be arranged in a user&#39;s ear canal to transmit sound generated by the BTE unit to a tympanic membrane of the user. The mounting insert&#39;s diameter is adapted to at least have the same diameter as a ear canal diameter of a user to close the ear canal of the user. Furthermore the mounting insert comprises at least one internal vent pathway, which is located on the circumference of the core hole of the flexible mounting insert. 
     One aspect of the invention is to reduce the occlusion effect by integrating a vent pathway in the core hole. Another aspect is the reduction of the acoustic feedback effect by using an acoustic tube to transmit the sound from the BTE unit to the ear canal, as backscattered sound does not reach the microphone of the hearing device and the backscattering is reduced by the vent pathways in the core hole. Further a comfortable fit in the ear canal is provided, as the mounting insert which adjoins to the ear canal is made of a flexible material. The design of the vent pathway allows to produce smaller dome sizes with the need of less material. The vent pathway size can be adjusted to the user needs increasing the design freedom of the mounting insert. Further the vent pathway is less likely to be blocked through squeezing of the mounting insert in the ear canal. Another aspect of the invention is that the vent pathway is less prone to be blocked with ear wax, as it is part of the core hole, which reduces the need for cleaning the device. 
     The sound transmitting core hole of the mounting insert can also partly contain a sound impermeable material, e.g. sound filter elements like gratings or sieves with small holes which transmit the sound. There can also be a number of gratings or sieves consecutively arranged in the core hole, whose holes do not necessarily have to be aligned and which can be used to control the sound transmission and the vent pathway size. 
     The vent pathway on the circumference of the core hole may be a groove in the material. Also a larger number of grooves can be arranged on the perimeter of the core hole. The grooves can be arranged on the whole circumference, preferably they only occupy a maximum of 340° of the circumference, such as a maximum of 300°, respectively preferred 180° of the circumference of the core hole. The size of the grooves can be designed in dependence of the needs of a user, with larger grooves for higher venting pathways. The form of the grooves can be cylindrical, cubical or of a similar geometric form. 
     The vent pathway can start at the distal end or the proximity of the distal end of the thin acoustic tube and end at a proximal end of the flexible mounting insert or a proximal end of a projection of the flexible mounting insert or in the proximity of the proximal end of a projection of the flexible mounting insert, which encloses the vent pathway. The length of the vent pathways can be shorter if squeezing of the mounting insert is expected to be smaller and longer for stronger squeezing of the mounting insert. 
     A wax filter element adapted to be at least partly permeable for sound transmission and at least partly impermeable for material transmission can be placed in front of the core hole or inside of the core hole to stop ear wax to enter the core hole and damp sound reflected from the ear canal. Preferably the wax filter element is coated with a material or has a specialized surface form that dampens sound to increase the sound dampening effect. In one embodiment the wax filter element has a grating with a fine mesh to stop wax from entering the core hole. The grid size can be varied to adjust the dampening and ear wax filtering effect. An alternative embodiment includes a filter bridge that is preferably located in front of the core hole or in close proximity to the core hole and shields the core hole from ear wax. 
     One aspect of the invention is therefore to prevent ear wax to close the vent pathway, as the wax filter element guards both the sound transmission core pathway through the core hole as well as the vent pathway due to the arrangement of the wax filter element and the vent pathway, e.g. in the core hole. 
     In a preferred embodiment the distal end of the thin acoustic tube is a ball joint with a hole for sound transmission and a spherical shape, which is adapted to adjoin to the flexible mounting insert. The spherically shaped distal end of the thin acoustic tube can act as a tread to form a stable connection to the flexible mounting insert. 
     Preferably the flexible mounting insert comprises at least two materials. The innermost material of the mounting insert is preferably the hardest of the materials, intended to adjoin to the acoustic tube and the outermost material is the most flexible and soft material, intended to adjoin to an ear canal of a user. In one preferred embodiment the hardest and innermost part of the flexible mounting insert adjoins to the spherically shaped distal end of the acoustic tube respectively it adjoins to the ball joint. The innermost part of the flexible mounting insert preferably contains the vent pathways on its circumference. The flexible mounting insert adjoined to the ball joint can have an increased articulation and is able to better adapt to the form of the ear canal, allowing an angle between the acoustic tube and the flexible mounting insert adjoined to the acoustic tube. 
     The flexible mounting insert connected to a ball joint with venting pathways in the innermost art of the flexible mounting insert which adjoins to the ball joint is in itself an invention that can also be implemented in other hearing devices without the need of an acoustic tube. Preferably a thin tube with an electrical lead connecting the BTE unit and a speaker unit (receiver unit) can be used instead of the acoustic tube, wherein the distal end of the speaker unit forms the ball joint or is connected to the ball joint. The receiver of the hearing device can for example be housed in the speaker unit and the lead transmits signals from the amplifier of the BTE unit to the receiver located in the ear canal. 
     In another embodiment the flexible mounting insert and/or the acoustic tube can include sound pressure level sensors on their distal sides, where distal means the side in the direction of the ear canal. The sensors are adapted to measure a sound pressure level on on the distal side. Also other sensors are possible, which measure other parameters of the acoustic environment. The hearing device can also include sensors on the proximal side, which is the side in the direction away from the ear canal to the outside of the ear. The proximal sensors can measure parameters of the acoustic environment on the outside of the ear. A processing unit can then determine the difference between the parameters of the acoustic environments on the distal and proximal sides of the mounting insert to generate a control signal or save the data in a memory unit. 
     In a preferred embodiment the core hole has an entrance area in the dome shape part of the flexible mounting insert. The entrance area can include filter element, e.g. a sound filter element. In one embodiment the sound filter element is comprised of consecutively arranged filter elements. Preferably the filter element includes mechanical or micromechanical means for rotation of individual filter elements of the sound filter element. 
     In another embodiment at least part of the material of the flexible mounting insert and/or a part of the material at the proximity of the distal end of the thin acoustic tube comprise piezoelectric properties. Applying a current to the material parts with piezoelectric properties can lead to a volume increase of the material, which for example decreases the size of the venting pathway. The piezoelectric materials can also be used to rotate the consecutively arranged filter elements, e, g, gratings, sieves or similar filters, to each other, leading to a misalignment of the filters, which can lead to a decreased sound transmission or decreased venting effect, as smaller transmission area is available for sound to be transmitted from the ear canal to the outside of the ear. 
     Preferably the processing unit is connected to the sensors that monitor the acoustic environment. The processing unit can generate control signals in dependence of the difference between the parameters of the acoustic environments on the distal and proximal sides of the mounting insert. The control signals can be transmitted to the mechanical, micromechanical or piezoelectrical means, which are configured to increase or decrease the venting pathway and the sound transmission by rotation of filter elements and expansion or contraction of the material with piezoelectric properties to optimize the sound experience of a user. 
     In another embodiment the wax filter element is at least partly of a material with piezoelectrical properties. Preferably at least the grating of the wax filter element has piezoelectrical properties. The wax filter element can also be connected to the processing unit which is connected to the sensors that monitor the acoustic environment and controls the size of the venting pathways. Applying current to the wax filter element can increase or decrease the sound transmission by increasing or reducing the size of the holes in the wax filter element, which further allows to control the possible amount of ear wax or fluid that enters through the filter. 
     According to an alternative embodiment instead of the thin acoustic tube a lead connecting the amplifier of the BTE unit with the receiver is provided. The receiver is configured to be arranged in a user&#39;s ear canal to transmit signals generated by the amplifier to the receiver. The receiver is enclosed in a receiver unit which is configured to be connected to the flexible mounting insert. The receiver is configured to generate sound to be transmitted to a tympanic membrane of the user. In a preferred embodiment, a ball joint forms the distal end of the receiver unit or is connected to the distal end of the receiver unit, and the ball joint has a hole for sound transmission and a spherical shape, which is adapted to adjoin to the flexible mounting insert. 
    
    
     
       BRIEF DESCRIPTION OF ACCOMPANYING FIGURES 
       The present invention will be more fully understood from the following detailed description of embodiments thereof, taken together with the drawings in which: 
         FIG. 1  shows a schematic illustration of a human ear with a hearing device with a BTE (Behind-The-Ear) unit connected to an acoustic tube that is connected to a mounting insert that adjoins to the ear canal of the human ear,  FIG. 1A  shows an ITE (In the Ear) unit, where the acoustic tube is very short and  FIG. 1B  shows the ITE unit where the acoustic tube is very short, such that the microphone, sound processor and battery are all seated inside the ear canal according to an embodiment of the invention; 
         FIG. 2  shows a schematic illustration of prior art vented domes with a venting hole in two perspectives; 
         FIG. 3  shows a schematic illustration of a mounting insert with dome shape and a filter bridge element in front of its core hole according to an embodiment of the invention; 
         FIG. 4  shows a longitudinal cut through the mounting insert of  FIG. 3  with details of the venting pathway according to an embodiment of the invention: 
         FIG. 5  shows another perspective of an embodiment of a mounting insert with dome shape and one vent groove according to an embodiment of the invention; 
         FIG. 6  shows a second embodiment of a mounting insert with dome shape and four vent grooves according to an embodiment of the invention; 
         FIG. 7  shows a ball joint connected to another embodiment of the mounting insert with dome shape and vent grooves in a longitudinal cut according to an embodiment of the invention; 
         FIG. 8  shows a mounting insert with an inserted wax filter element and details of the wax filter element according to an embodiment of the invention; 
         FIG. 9  shows another embodiment of a mounting insert with dome shape and vent grooves in the core hole that elongate to the end of a core pathway projection according to an embodiment of the invention; 
         FIG. 10  shows the ball joint connected to the mounting insert of  FIG. 7  in angled position according to an embodiment of the invention; 
         FIG. 11  shows a mounting insert connected to a speaker unit (receiver unit) according to an embodiment of the invention; 
         FIG. 12  shows a mounting insert connected to a speaker unit and the cable connection to the BTE unit according to an embodiment of the invention; 
         FIG. 13  shows a mounting insert connected to an acoustic tube according to an embodiment of the invention; 
         FIG. 14  shows an embodiment of a filter element for the mounting insert according to an embodiment of the invention; 
         FIG. 15  shows another embodiment of a sound filter element for the mounting insert according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a hearing device  1  with a Behind-The-Ear (BTE) unit  10  mounted on an ear  12  of a user. The BTE unit  10  has a microphone  14 , an amplifier  16 , a power source  18  and a receiver  20 . The microphone  14  records sound and generates electrical signals, which are amplified in the amplifier  16  and transmitted to the receiver  20 . The receiver  20  uses the amplified electrical signals to generate sound, which is guided to an acoustic tube  22 , which has a proximal end  24  connected to the BTE-unit  10  by an acoustic plug  26  and a distal end  28 . The acoustic tube  22  runs along the form of the ear  12  through the concha  30  into an ear canal  32  of a user. The sound generated by the receiver  20  in the BTE unit  10  is transmitted through the acoustic tube  22  to a mounting insert  34  which adjoins to the distal end  28  of the acoustic tube  22 . The mounting insert  34  is adapted to adjoin to the ear canal  30  of the user, where the sound enters a cavity  36  and finally reaches a tympanic membrane  38  of the user. 
       FIGS. 1A and 1B  shows an ITE (In the Ear) unit, where the acoustic tube  22  is very short, such that the microphone, sound processor and battery are all seated inside the ear canal  36  as seen in  FIG. 1B . All the venting problems and solutions presented below with respect to the RITE, and BTE solutions will also apply to ITE solutions as presented in  FIGS. 1A and 1B . In  FIG. 1B  the ITE has its dome shaped part  40  placed in the bony part  15  of the ear canal  36 , and here the venting problems may differ slightly from the venting problems of dome shaped parts placed outside of this bony part. Firstly, the vent will usually have to be smaller, and secondly it is most important that the vent canal is open when the hearing aid  11  is inserted or pulled out, as otherwise the tympanic membrane  38  may be subject to higher than ambient or lower than ambient pressures as the domes shaped part travels the length of the bony section in the same way a piston travels the length of a cylinder. This may cause pain or injury to the person wearing the hearing aid  11 . 
       FIG. 2  shows a prior art mounting insert  34  with a dome shaped part  40  that has a core hole  42  and a vent hole  44 . The Gore hole  42  is the entrance to a core pathway  46  which is enclosed by a core pathway projection  48 . The core pathway  46  is mainly used to transmit sound. The vent hole  44  is in front of a venting slit  50 , both being part of the vent pathway, which is intended to equalize pressure in the inside and outside of the ear canal cavity  36 . A mounting insert cavity  62  allows the dome shaped part  40  to adjust to the ear canal  32  through squeezing of the dome shaped part  40  in the direction of the core pathway projection  48 . 
       FIG. 3  presents a first embodiment of a flexible mounting insert  34  with a filter bridge  54  in front of the core hole  42  intended as a wax filter. The filter bridge  54  of this embodiment contains a small filter bridge hole  56  and is affixed to the dome shaped part  40  of the flexible mounting insert  34  with a filter bridge affixture  58 . Sound can pass either through the filter bridge hole  56  or through an indirect pathway along the sides of the filter bridge  54  into the core hole  42 . Ear wax is stopped by the filter bridge  54 , as the ear wax is too large to pass neither the filter bridge hole  56  nor the indirect pathway along the sides of the filter bridge  54  into the core hole  42 . 
       FIG. 4  is a longitudinal cut through the first embodiment of the flexible mounting insert  34 . Behind the filter bridge  54  is an entrance area  60  of the core hole  42  which is enclosed and formed by the dome shaped part  40  of the mounting insert  34 . The entrance area  60  may contain additional filter elements (not shown). The entrance area  60  adjoins to a cavity  62  adapted to enclose the acoustic tube  22 . A tread cavity  64  with a larger diameter than the cavity  62  for the acoustic tube  22  is intended to fasten the acoustic tube  22  in the mounting insert  34 . The acoustic tube  22  contains the core pathway  46  which is intended to transmit sound from the receiver  20  of the BTE-unit  10  to the tympanic membrane  38  in the ear canal  32  (not shown). The cavity  62  contains vent grooves  66 , which are intended as vent pathways, in the material of the perimeter of the cavity  62 . The vent grooves  66  extend to an outlet  68  which increases the diameter of the cavity and ends at the proximal end  49  of the core pathway projection  48 . 
       FIG. 5  shows a second embodiment of the flexible mounting insert  34  which contains only one vent groove  66  in a box-like form along the circumference of the core hole  42  extending to the outlet  68  which ends with the proximal end  49  of the core pathway projection. 
       FIG. 6  presents a third embodiment of the flexible mounting insert  34  which is almost identical to the second embodiment, but contains four smaller sized box-like vent grooves  66  which are arranged symmetrically around the core hole  42 . The vent grooves  66  extend to the outlet  68 , which ends at the proximal end  49  of the core pathway projection  48 . 
     In  FIG. 7  an acoustic tube  22  with a distal end  28  with a ball joint  70  having a spherical shape is connected to the mounting insert  34 . The mounting insert  34  is comprised of two parts, an inner core part  72  which is of a hard material and an outer part  74  which is of a softer and flexible material. The inner core part  72  adjoins to the ball joint  70  which encloses the core pathway  46 . Vent grooves  66  are located on the circumference of the inner core part  72  running around the ball joint  70  and end at the proximal end  49  of the core pathway projection  48  creating a vent pathway. As the inner core part  72  is of a harder material it can be clicked on the ball joint  70  creating a stable connection. The inner core part  72  contains a wax filter element  76  between an inner part cavity  78  and the entrance area  60  of the core hole  42 . The core hole  42  can contain further filter elements (not shown). The softer material of the outer part  74  enclosing the inner core part  72  is intended to generate a comfortable fit in the ear canal  32  of a user. 
     As an option a distal sensor  73  is configured to measure parameters of the acoustic environment in the ear canal cavity  36 . The parameters are enclosed in an electrical signal and sent to a processing unit  75 . The processing unit is further connected to a proximal sensor  77 , which measures parameters of the acoustic environment outside of the ear canal cavity  36  and sends these parameters as an electrical signal to the processing unit  75 . The processing unit  75  can for example compare the sound pressure levels between the ear canal cavity  36  on the distal side of the flexible mounting insert  34  in and on the proximal side of the flexible mounting insert  34 . The processing unit  75  can then e.g. generate an electrical signal from the difference in sound pressure levels and send control signals over the electrical leads  80  to control the size of the vent grooves  66  e.g. by mechanical means such as nitinol wires or piezoelectrical means or the size of the grating  82  ( FIG. 8 ) of the wax filter element  76 . 
       FIG. 8  presents a fourth embodiment of the flexible mounting insert  34  which contains a removable wax filter element  76 . The wax filter element  76  is located behind the core hole  42  in the core pathway  46  and enclosed by the core pathway projection  48 . A wax filter grating  82  has holes  84  that allow passage of sound, while the grating  82  prevents ear wax to enter the core pathway  46  of the mounting insert  34 . The wax niter element  76  contains a vent groove  66 , which is intended for venting. The vent groove  66  is therefore located behind the wax filter grating  82 , which means that the wax filter element  76  protects the core pathway  46  for sound transmission and the vent pathway of the vent groove  66  from becoming blocked by ear wax. Preferably the wax filter grating  82  contains a coating on its distal side oriented into the ear canal, which dampens sound. Also a coating which interacts with ear wax to liquefy the ear wax can be applied on the wax filter element  76 . 
       FIG. 9  shows a fifth embodiment of the flexible mounting insert  34  which is similar to the third embodiment, with the major difference that the vent grooves  66  are elongated to the proximal end  49  of the core pathway projection  48 . 
       FIG. 10  shows the acoustic tube  22  with ball joint  70  connected to the mounting insert  34  of  FIG. 7  in an angled position of the mounting insert  34  with respect to the acoustic tube  22  (without sensors and processing unit). A tread  86  on the outer circumference of the acoustic tube  22 , which is located in the proximal vicinity of the spherically shaped ball joint  70  limits the articulation of the flexible mounting insert  34 . The core pathway projection  48  is in contact with the tread  86  closing one region of the vent groove  66 , while in the other regions a vent groove exit  88  is maintained as a vent pathway. 
       FIG. 11  presents a speaker unit (receiver unit)  90  connected to a flexible mounting insert  34 . A speaker tread  92  that is enclosed by a flexible speaker connection element  94  is fastened in the tread cavity  64  to form a stable connection between the speaker unit  90  and the flexible mounting insert  34 . The speaker tread  92  can also be a ball joint and the flexible mounting insert  34  can be formed from a hard inner core part  72  and a flexible outer part  74  (not shown). The flexible speaker connection element  94  connects to a speaker unit housing  96  which contains a speaker (receiver)  98 , which generates sound from electrical signals supplied to the speaker  98  by a wire  100 . The wire  100  is enclosed by a sleeve  102 , which forms a lead  104 . The lead  104  has an electrical plug  106  and connectors  108  which are connected to the BTE unit  10  where the electrical signals are generated from sound recorded by the microphone  14  (see  FIG. 12 ). The distal end of the speaker unit (receiver unit)  90  can also be formed as a ball joint and connect to the flexible mounting insert  34  (not shown). 
       FIG. 13  shows a flexible mounting insert  34  connected to an acoustic tube  22 . A tread  110  of the acoustic tube  22  is fastened in the tread cavity  54  to form a stable connection between acoustic tube  22  and flexible mounting insert  34 . The tread  110  is part of a flexible acoustic tube housing  112  which is connected to the distal end  28  of the acoustic tube  22 . Sound generated by the receiver  20  in the BTE unit  10  is transmitted through the acoustic tube  22  along the core pathway  46  to the ear canal  32 , where it is received from the tympanic membrane  38  of the user. 
     In  FIG. 14  a first embodiment of a sound filter element  114  is presented. The sound filter element  114  is comprised of a first filter element  115 , a second filter element  118 , a third filter element  120  and a fourth filter element  122 , which are consecutively arranged. The sound filter element  114  can for example be placed in the entrance area  60  of the core hole  42  to control the amount of sound transmitted through the core pathway  46 . The first filter element  115  has small sound transmission holes  124  arranged in the center of the filter element  114  for transmitting sound and bridging elements  125  connected to the core hole  42  walls of the flexible mounting insert  34 . A sound damping material forms the core of the filter element  128 , which partly blocks the core pathway  46 . Large vent holes  130  allow for sound transmission for venting along a vent pathway  132 . The second filter element  118  has a large sound transmission hole  134  to allow for sound transmission from the small sound transmission holes  124 . Grooves  66  at the circumference of the second filter element  118  allow for venting, while the sound is partly blocked by the filter element core  128 . To control the size of the sound transmission along the core pathway  46  and the venting along the vent pathway  132  it is possible to rotate the filter elements  116 ,  118 ,  120  and  122 , e.g. by mechanical means or piezoelectrical means. The filter elements  116  and  118  are rotated in clockwise direction  136 , while the filter elements  120  and  122  are rotated in counter clockwise direction  138  to control the sizes of the core pathway  46  and the vent pathway  132 . 
       FIG. 15  shows a second embodiment of a sound filter element  114 ′. The sound filter element  114 ′ has a filter element core  128  with the core pathway  46  in its center and vent grooves  66  of different sizes on its circumference. The grooves  66  serve as vent pathways  132  to a vent pathway exit  140 . The size of the vent pathway  132  can be adjusted in dependence of the orientation of the grooves  66  of the sound filter element  114 ′. The orientation of groove  66  in  FIG. 15  shows only a small vent pathway  132 . Rotation of the sound filter element  114 ′ by 180° leads to a larger vent pathway  132  (not shown). The rotation can be possible by mechanical means, piezoelectrical means or other means. The sound filter element  114 ′ is preferably a disposable means for sound filtering and venting. 
     It should be appreciated that reference throughout this specification to “one embodiment” or “an embodiment” or features included as “may” or “can” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, it is emphasized and should be appreciated that two or more references to “an embodiment” or “one embodiment” or “an alternative embodiment” or features included as “may”/“can” in various portions of this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined as suitable in one or more embodiments of the invention. 
     Throughout the foregoing description, for the purposes of explanation, numerous specific details were set forth in order to provide a thorough understanding of the invention. 
     Accordingly, the scope of the invention should be judged in terms of the claims which follow. 
     REFERENCE SIGNS 
       1  hearing device 
       10  BTE (Behind-The-Ear) unit 
       11  ITE (In The Ear) Unit 
       12  ear 
       13  ITE casing 
       14  microphone 
       15  Bony part 
       16  amplifier 
       18  power source 
       20  receiver 
       22  acoustic tube 
       24  proximal end 
       26  acoustic plug 
       28  distal end 
       30  concha 
       32  ear canal 
       34  mounting insert 
       36  ear canal cavity 
       38  tympanic membrane 
       40  dome shape part 
       42  core hole 
       44  vent hole 
       46  core pathway 
       48  core pathway projection 
       49  end of core pathway projection 
       50  venting slit 
       52  mounting insert cavity 
       54  filter bridge 
       56  filter bridge hole 
       58  filter bridge affixture 
       60  entrance area of the core hole 
       62  cavity for the acoustic tube 
       64  tread cavity 
       66  vent groove 
       68  outlet 
       70  ball joint 
       72  inner core part of the mounting insert 
       73  distal sensor 
       74  outer part of the mounting insert 
       75  processing unit 
       76  wax filter element 
       77  proximal sensor 
       78  inner part cavity 
       80  electrical lead 
       82  wax filter grating 
       84  hole of the wax filter element 
       86  tread at the ball joint 
       88  vent groove exit 
       90  speaker unit (receiver unit) 
       92  speaker tread 
       94  flexible speaker connection element 
       96  speaker unit housing 
       98  speaker (receiver) 
       100  wire 
       102  sleeve 
       104  lead 
       106  electrical plug 
       108  connector 
       110  acoustic tube housing tread 
       112  flexible acoustic tube housing 
       114  sound filter element 
       116  first filter element 
       118  second filter element 
       120  third filter element 
       122  fourth filler element 
       124  small sound transmission hole 
       126  bridging element 
       128  filter element core 
       130  large vent hole 
       132  vent pathway 
       134  large sound transmission hole 
       136  clockwise rotation direction 
       138  counter clockwise rotation direction