Abstract:
A soft custom ear mold ( 300 ) comprising: an inner ear mold part ( 100 ) consisting of a first bushing ( 101 ), a sound tube ( 102 ) and an ear wax guard bushing ( 103 ), and an outer ear mold part ( 200 ) that is adapted to fit an individual ear canal and comprises a sound conduit having holding means adapted to engage said inner part ( 100 ). The holding means defines the correct positioning of said inner part ( 100 ) in the sound conduit of said outer part ( 200 ) whereby a precise and stable positioning of the ear wax guard bushing ( 103 ) in the soft custom ear mold ( 300 ) is provided. The invention also relates to a hearing aid comprising such an ear mold ( 300, 900 ), a method for manufacturing such an ear mold and a tool for carrying out a part of said manufacturing method.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation-in-part of International application No. PCT/EP2011/068011, filed on Oct. 14, 2011, published as WO-A1-2013053402, and incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to hearing aids. The invention, more specifically, relates to a soft custom ear mold for hearing aids. The invention further relates to a method of manufacturing a soft custom ear mold. The invention, in particular, relates to a tool for use in the method. 
     In the context of the present disclosure, a hearing aid should be understood as a small, battery-powered, microelectronic device designed to be worn behind or in the human ear by a hearing-impaired user. Prior to use, the hearing aid is adjusted by a hearing aid fitter according to a prescription. The prescription is based on a hearing test, resulting in a so-called audiogram, of the performance of the hearing-impaired user&#39;s unaided hearing. The prescription is developed to reach a setting where the hearing aid will alleviate a hearing loss by amplifying sound at frequencies in those parts of the audible frequency range where the user suffers a hearing deficit. A hearing aid comprises one or more microphones, a battery, a microelectronic circuit comprising a signal processor, and an acoustic output transducer. The signal processor is preferably a digital signal processor. The hearing aid is enclosed in a casing suitable for fitting behind or in a human ear. 
     As the name suggests, Behind-The-Ear (BTE) hearing aids are worn behind the ear. To be more precise an electronics unit comprising a housing containing the major electronics parts thereof is worn behind the ear. An ear mold for emitting sound to the hearing aid user is worn in the ear, e.g. in the concha or the ear canal. In a traditional BTE hearing aid, a sound tube is used because the output transducer, which in hearing aid terminology is normally referred to as the receiver, is located in the housing of the electronics unit. In some modern types of hearing aids a conducting member comprising electrical conductors is used, because the receiver is placed in the earpiece in the ear. Such hearing aids are commonly referred to as Receiver-In-The-Ear (RITE) hearing aids. In a specific type of RITE hearing aids the receiver is placed inside the ear canal. This is known as Receiver-In-Canal (RIC) hearing aids. 
     2. Prior Art 
     Basically two different types of ear molds are offered today. The first type may be denoted custom ear molds and are characterized in that the shape of a specific ear canal is obtained and that the ear mold is subsequently manufactured such that it corresponds to the specific ear canal. At present the shape of the ear canal is typically obtained using an ear impression but this need not be the case since e.g. various digital scanning methods can also provide the shape of a specific ear canal. The second type may be denoted instant fit ear molds and are characterized in that they have not been adapted to the shape of a specific ear canal. Instead this type of ear molds has been adapted to cover a wide range of ear canals. Generally the custom ear molds are advantageous compared to the instant fit type in that they provide a secure and precise fit in the ear canal, whereby the ear molds will not tend to fall out of the ear, and the leakage of sound around the ear mold will be small whereby the risk of acoustic feedback is reduced. 
     The respective custom and instant-fit ear molds may further be sub-divided into soft and hard ear molds. The hard custom ear molds may e.g. be manufactured using rapid prototyping techniques. Further details concerning such a method can be found e.g. in U.S. Pat. No. 5,487,012. 
     Generally the hard ear molds are advantageous in that the hard materials provide high acoustic attenuation. This is important in order to control sound leakage, and hereby acoustical feedback, from an interior sound channel in the ear mold and towards the surroundings outside the ear mold. The hard ear molds may be disadvantageous in that the hearing aid fitter will typically have to send the ear canal impressions to a remote ear mold manufacturing site, which has the consequence that the hearing aid user has to wait a few days before he can obtain his new hearing aid with hard custom ear molds. 
     The soft custom ear molds are typically manufactured by a hearing fitter, who obtains an impression of a specific ear canal and uses a negative of the impression to mold a soft ear mold in e.g. silicone. The soft custom ear molds are advantageous in that they may provide an improved comfort relative to hard ear molds, in that they may reduce sound leakage—even compared to hard custom ear molds, and in that local hearing aid fitters can manufacture this type of ear mold in-house. The soft ear molds may be disadvantageous in that the acoustic attenuation of the available soft ear mold materials is low compared to the available hard ear mold materials. 
     As already disclosed the soft ear mold is preferably manufactured in silicone. A preferred silicone is the Biopor, which is biocompatible. However, other resilient materials, such as soft acrylic may also be applied. Generally, the soft ear mold should preferably be manufactured from a material having a hardness which is below 80 measured on the Shore durometer type A scale (see the standard ASTM D2240 for description of the test). This is often written as Shore 80A. Preferably, the hardness is below Shore 60A, and more preferably the hardness is in the range from Shore 20A to Shore 45A. 
     In order to solve the problem of the limited acoustic attenuation of the soft ear mold materials it has been proposed in the art to insert a sound tube of a highly acoustic attenuating material into the sound conduit of the soft ear mold. It has been proposed to use e.g. Polyvinyl Chloride (PVC) and Polyurethane (PUR) as sound tube material. These materials are relatively soft and it has therefore been suggested to insert the sound tube into the soft ear mold by:
         putting a hard mounting tool through the sound conduit of the ear mold such that the first end of the mounting tool is on the first side of the ear mold and the other end of the mounting tool is on the other side of the ear mold,   fixing the sound tube onto a hard mounting tool,   pulling the mounting tool, and hereby the sound tube, back through the sound conduit of the ear mold,   removing the hard mounting tool from the sound tube, and   trimming the ends of the sound tube to make them flush with the ear mold.       

     In order to keep the sound tube at the correct position inside the soft ear mold it has been suggested to achieve this by:
         providing a soft ear mold wherein the sound conduit is adapted to accommodate a bushing,   putting a hard mounting tool through the sound conduit of the ear mold such that the first end of the mounting tool is on the first side of the ear mold (the side adapted to face outwards when inserted in an ear canal) and the other end of the mounting tool is on the other side of the ear mold,   fixing a hard bushing to a first end of the sound tube,   engaging the first end of the mounting tool with the second end of the sound tube,   pulling the mounting tool, and hereby the sound tube and the bushing, back through the sound conduit of the ear mold until the bushing is seated correctly inside the ear mold,   removing the hard mounting tool from the sound tube, and   trimming the second end of the sound tube flush with the ear mold.       

     The soft ear molds may be further be disadvantageous in that traditional ear wax guards, such as disclosed in e.g. U.S. Pat. No. 9,795,562, cannot be used. The main reason for this is that the soft ear molds are not capable of accommodating an ear wax guard or an ear wax guard bushing in the same manner as a hard ear mold. It has therefore become common practice to use the soft ear molds without an ear wax guard. A consequence of this is that the sound tube has to be cleaned regularly which is more cumbersome than simply replacing an ear wax guard. 
     It is therefore a feature of the present invention to overcome at least these drawbacks and provide a soft custom ear mold that permits the use of an ear wax guard. 
     It is another feature of the current invention to provide a method for manufacturing a soft custom ear mold. 
     SUMMARY OF THE INVENTION 
     The invention, in a first aspect, provides a method for manufacturing a soft custom ear mold having an ear wax guard bushing, comprising the steps of providing an outer part of a soft custom ear mold with a through going conduit having holding means, providing an inner part of a soft custom ear mold comprising a first bushing, a sound tube and an ear wax guard bushing arranged such that the first bushing is fixed to the sound tube and a first end of the ear wax guard bushing is fixed to a first end of the sound tube, providing an elongated tool with an end adapted for engaging a second end of the ear wax guard bushing, putting the elongated tool through the soft custom ear mold conduit, fixing the elongated tool to the second end of the ear wax guard bushing; inserting the inner part into the ear mold conduit by pulling the elongated tool having said inner part attached, through the ear mold conduit until said first bushing is properly positioned in said holding means, and disengaging the elongated tool from the ear wax guard bushing. 
     This provides a manufacturing method that is simple to carry out and only requires the use of inexpensive tools. 
     The invention, in a second aspect, provides a soft custom ear mold comprising: an inner ear mold part that comprises a first bushing, a sound tube and an ear wax guard bushing, an outer ear mold part that is adapted to fit an individual ear canal and comprises a sound conduit having holding means adapted to engage the first bushing of said inner part, wherein said holding means defines the correct positioning of said inner part in the sound conduit of said outer part whereby a precise and stable positioning of the ear wax guard bushing in the soft custom ear mold is provided. 
     This provides a soft custom ear mold that permits the use of an ear wax guard that can be replaced by the hearing aid user in a simple manner. 
     Further advantageous features appear from the dependent claims. 
     Still other features of the present invention will become apparent to those skilled in the art from the following description wherein the invention will be explained in greater detail. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       By way of example, there is shown and described a preferred embodiment of this invention. As will be realized, the invention is capable of other different embodiments, and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. In the drawings: 
         FIG. 1  illustrates a sound tube, a first bushing and a wax guard bushing in assembled form according to an embodiment of the invention; 
         FIG. 2  illustrates the sound tube, the first bushing and the wax guard bushing of  FIG. 1  in unassembled form; 
         FIG. 3  illustrates an outer part of a soft custom ear mold according to an embodiment of the invention; 
         FIG. 4  illustrates an elongated tool adapted for engaging a wax guard bushing according to an embodiment of the invention; 
         FIG. 5  illustrates a first stage in a method for manufacturing a soft custom ear mold according to an embodiment of the invention; 
         FIG. 6  illustrates a second stage in a method for manufacturing a soft custom ear mold according to an embodiment of the invention; 
         FIG. 7  illustrates a third stage in a method for manufacturing a soft custom ear mold according to an embodiment of the invention; 
         FIG. 8  illustrates a wax guard and a wax guard insertion and extraction tool according to an embodiment of the invention; 
         FIG. 9  illustrates a receiver module adapted for insertion in a soft custom ear mold according to an embodiment of the invention; 
         FIG. 10  illustrates the soft custom ear mold according to an embodiment of the invention with the receiver module of  FIG. 9  inserted; 
         FIG. 11  illustrates a first stage in a method for manufacturing a soft custom ear mold according to an embodiment of the invention; 
         FIG. 12  illustrates a second stage in a method for manufacturing a soft custom ear mold according to an embodiment of the invention; and 
         FIG. 13  illustrates a third stage in a method for manufacturing a soft custom ear mold according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference is now made to  FIG. 1 , which illustrates an inner part  100  of a soft custom ear mold. The inner part  100  comprises a first bushing  101 , a sound tube  102  and a wax guard bushing  103 . The first bushing  101  is fixed onto a first end of the sound tube  102 , and the wax guard bushing  103  is fixed onto the second end of the sound tube  102 . Both bushings are fixed onto the sound tube using a press-fit between the relatively hard bushings  101  and  103  and the comparatively soft sound tube  102 . 
     The first bushing  101  is adapted such that it comprises a bend. This feature makes the first bushing  101  especially advantageous when inserted in the outer part of a soft ear mold since the sound conduit of the outer part of the soft custom ear mold may otherwise tend to collapse, in or around the bend, as may otherwise be imparted on insertion into an ear canal. 
     The sound conduit may comprise such a bend simply due to the shape of the ear canal or due to the placement of a receiver in the concha, in which case it may be required that the sound conduit bends from the plane of the concha and into the ear canal, e.g. as shown in WO-A1-2010040351. 
     The first bushing  101  is adapted such that it can be accommodated in a corresponding structure in the outer part  200  of the soft custom ear mold whereby the inner part  100  of the soft custom ear mold is fixed at the desired position inside the outer part  200  of the soft custom ear mold. Additionally the first bushing  101  comprises holding means adapted to detachably fix a receiver or a sound tube to that end of the first bushing  101  that is not fixed to the sound tube  102 . Thus in the first case the first bushing is adapted for a receiver-in-the-ear (RITE) type hearing aid and in the latter case the first bushing is adapted for a traditional behind-the-ear (BTE) type hearing aid. The first case is further described below with reference to  FIGS. 9-10  and the latter case is further described with reference to  FIGS. 11-13 . 
     As already discussed the sound tube  102  is preferably manufactured in materials such as Polyvinyl Chloride (PVC) or Polyurethane (PUR) that provide a suitable flexibility for insertion in the sound conduit of the outer part  200  of an ear mold while decreasing the acoustic leakage from the sound conduit. 
     The wax guard bushing  103  is adapted such that it can receive a replaceable ear wax guard  104 . Such replaceable ear wax guards are well known within the art of hearing aids and are disclosed in e.g. U.S. Pat. No. 6,795,562 as already discussed above. 
     Thus it has to appreciated that the inner part  100  of the ear mold comprising the two bushings  101  and  103  and the sound tube  102  when inserted in the corresponding outer part  200  of the ear mold provide a soft custom ear mold  300  (see e.g.  FIG. 10 ) that can accommodate the use of traditional replaceable ear wax guards  104 , whereby the cleaning and maintenance of the soft custom ear mold  300  will become easier and the performance of the ear mold generally improve because the sound output opening of an ear mold having an ear wax guard will be less prone to clogging with ear wax. 
     Further it has to be appreciated that it is considerably easier to adapt the outer part  200  of the ear mold such that it can accommodate the first bushing  101  as opposed to adapting the outer part  200  of the ear mold to accommodate the wax guard bushing  103  because the first bushing  101  is larger and because the first bushing  101  is accommodated fully in the interior of the outer part  200  of the ear mold (as opposed to in an opening of the outer part  200  of the ear mold) which makes positioning and fixation of the inner part  100  in the outer part  200  of the soft custom ear mold less difficult to achieve. In the present context this presents a significant advantage because the soft custom ear molds are generally manufactured in-house by a hearing aid fitter using only simple manufacturing equipment. Furthermore the ear wax guard bushing  103  will be securely fixed to the inner part  100  of the soft custom ear mold and will therefore not tend to drop out from the soft custom ear mold. 
     In another embodiment the outer part  200  of the soft custom ear mold is manufactured using a negative of an ear canal impression as outer surface of the mold form and wherein the inner structure of the sound conduit is formed by using a mold insert to mold around. In a further embodiment the mold insert comprises a hard cylindrical mold insert part that may be inserted into a softer hollow sleeve having an outer structure corresponding to the desired inner structure of the sound conduit of the outer part of the soft custom ear mold. This type of mold insert allows the manufacture of a less pliable inner structure of the sound conduit, e.g. an inner structure adapted for snap fitting onto the first bushing whereby a more secure positioning and fixation of the inner part of the soft custom ear mold is provided. This can be achieved since the hard cylindrical insert part can be conveniently removed after molding independent of the inner structure of the sound conduit and after removal of this part the remaining hollow sleeve becomes very pliable and therefore easy to remove after molding even in case of a sound conduit with an inner structure having only limited pliability. 
     In variations according to the embodiment of  FIG. 1  the bushings  101  and  103  may be fixed onto the sound tube  102  using at least one of the methods selected from a group comprising press-fitting, snap-fitting, gluing, welding and two-component molding. Especially press-fitting and gluing can be combined. 
     Reference is now made to  FIG. 2 , which illustrates the first bushing  101 , the wax guard bushing  103  and the sound tube  102  as separated components prior to being assembled into the inner part  100  of the soft custom ear mold. 
     Reference is also made to  FIG. 3 , which illustrates the outer part  200  of a soft custom ear mold. 
     Reference is now made to the  FIGS. 4-8 , which illustrate a tool for mounting the inner part  100  of the soft custom ear mold in the outer part  200  of the soft custom ear mold  300  and corresponding steps of a method for mounting said inner part  100  in said outer part  200 . 
     Reference is first made to  FIG. 4 , which illustrates an elongated tool  400  with a pointed thread  401  adapted such that the tool  400  when engaging the inner surface of the wax guard bushing  103  enables the wax guard bushing  103  to be pulled through the outer part of the soft custom ear mold  200 . The tool comprises a forward part  402  with a narrow diameter adapted to fit inside a conduit and with a length sufficient to extend through the conduit to protrude at the other end. Further the tool comprises a rearward part  403  which is thicker and is adapted to provide a grip for manipulation. 
     Reference is now made to  FIG. 5 , which illustrates a first step in said method wherein said pointed thread  401  and forward part  402  of the tool  400  has been put through said outer part  200 . 
     Reference is then made to  FIG. 6  wherein said tool  400  has engaged said inner part  100 . 
     Reference is then made to  FIG. 7  wherein said elongated tool  400  with said inner part  100  attached has been pulled back through said outer part  200  until the first bushing  101  is seated in the corresponding structure (not visible in the drawing) in said outer part, whereby the soft custom ear mold  300  is completed. Subsequently the elongated tool  400  is disengaged from the wax guard bushing  103  by twisting the elongated tool  400  in the opposite direction of the rotation used for the initial engagement. The soft custom ear mold  300  is hereby provided with a wax guard bushing  103  that allows traditional replaceable wax guards to be used. 
     Finally reference is made to  FIG. 8 , which illustrates a traditional wax guard insertion and extraction tool  500  and a corresponding wax guard  104 . Further details may be found in U.S. Pat. No. 6,795,562. 
     Reference is now made to  FIGS. 9-10 , which illustrate insertion of a receiver module  600  in a soft custom ear mold  300  according to an embodiment of the invention. 
     Reference is first made to  FIG. 9 , which illustrates the receiver module  600  that comprises the receiver housing  601  and a corresponding electrical conductor  602  for connection to the external part of the RITE hearing aid. The receiver housing  601  comprises holding means adapted for engagement with a first bushing  101  of the inner part  100  of the soft custom ear mold  300 . 
     Reference is finally made to  FIG. 10 , which illustrates the soft custom ear mold  300  with the receiver module  600  inserted. 
     Reference is now made to  FIGS. 11-13 , which illustrate insertion of an inner part  700  in an outer part  800  of a soft custom ear mold according to an embodiment of the invention. 
     Reference is first made to  FIG. 11 , which illustrates the inner part  700  of the soft custom ear mold, the outer part  800  of the soft custom ear mold and an elongated tool  400 . 
     The inner part  700  comprises an external sound tube part  701 , a first bushing  702 , an internal sound tube part  703  and a wax guard bushing  103 ,  704 , wherein the first bushing  702  is adapted such that a precise and firm positioning of the sound tube assembly  700  inside the outer part  800  is obtained when the first bushing  702  engages corresponding holding means formed at the inner surface of the sound conduit of the outer part  800  of the soft custom ear mold. Further  FIG. 11  illustrates a first step in the method for mounting the inner part  700  in the outer part  800  of the custom ear mold, wherein said elongated tool  400  has been put through said outer part  800 . 
     Reference is then made to  FIG. 12  wherein said elongated tool  400  has engaged the wax guard bushing  103 ,  704  of said inner part  700 . 
     Reference is then made to  FIG. 13  wherein said elongated tool  400  with said inner part  700  attached has been pulled back through said outer part  800  until the first bushing  702  is accommodated in the corresponding structure (not visible in the drawing) in said outer part  800 , whereby the soft custom ear mold  900  is completed. Subsequently the elongated tool  400  will be disengaged from the wax guard bushing  103 ,  704  by twisting the elongated tool  400  in the opposite direction of the rotation used for the initial engagement. The soft custom ear mold  900  is hereby provided with a wax guard bushing  103  that allows traditional replaceable wax guards to be used. 
     According to the embodiment of  FIG. 11 , the internal  703  and external  701  parts of the sound tube is one single tube and the first bushing  702  is fixed to an intermediate part of the sound tube. In variations of the sound tube according to  FIG. 11 , the internal  703  and external  701  parts of the sound tube are two separate parts and the two ends of the first bushing are connected to the corresponding ends of the two sound tubes. 
     Other modifications and variations of the structures and procedures will be evident to those skilled in the art.