Abstract:
A method and appertaining system provide for automatically adding a wax guard to a hearing aid shell impression. The location of a canal, tip of the canal, and central line of the impression are automatically identified in a digital 3D representation of a hearing aid shell impression. A first wax guard plane is determined at a predefined flip distance from the canal tip along the central line, and a second wax guard plane is determined at a predefined canal tip offset distance from the canal tip along the central line. A size and position for a feature of the wax guard is calculated based on predefined parameters, and the wax guard is constructed utilizing the calculated side and position. The type of wax guard can be a bell bore design, an open design, a Philip design, or a flip design.

Description:
BACKGROUND 
       [0001]    The present invention provides protocols for automatic positioning and generation of a wax guard protection system for hearing instruments. The system is designed to interface with a feature recognition module, such as that described in U.S. patent application Ser. No. 11/612,616, entitled, “Intelligent Modeling Method and System for Earmold Shell and Hearing Aid Design”, filed Dec. 19, 2006, herein incorporated by reference. 
         [0002]    In general, a wax guard is a structure on the tip of a hearing aid shell used to protect the electronic components inside the shell from the wax entering from the patient&#39;s ear. Wax Guard systems are added to a large percentage of in-the-ear (ITE) hearing instrument products produced today, and many of the existing hearing instruments have some sort of wax protection systems associated with them. These systems are usually engineered to fit comfortably on most impressions and are empirically generated mostly by trial and error within 3D modeling media. 
         [0003]    Different types of wax guard systems currently exist in the hearing instruments industry, and include flip tops, Philips, open wax, and bell bores; these systems are usually implemented as a sculptural modification to the impression. Other types of wax systems are not sculptured onto the impression but rather are added to the impression as a 3D dimensional object designed externally and added to the hearing instrument. In certain instances both types of wax system are mutually used together. This present invention focuses on the former, where the implementation is adaptive to a given instrument. 
       SUMMARY 
       [0004]    The present invention is directed to a computerized and automatic method for the generation of wax guard systems using an adaptive algorithmic implementation. It includes embodiments for: 1) computerized automated and adaptive generation of a wax guard system for a given ear impression using dimensional features extracted from the impression. This ensures that each individual ear has a wax protection system generated specifically for it; 2) a software implementation of adaptive algorithms which allow different types of wax systems to be generated by simply altering parameters that control the wax guard generation protocols; and 3) a system for the adaptive generation of wax systems that also significantly improves the quality of the finished instrument. 
         [0005]    The positioning approach provided herein advantageously takes advantage of feature recognition algorithms and systems generated automatically for a given shell using advanced shell classification protocols, and provides a mechanism to position the wax guards automatically on the shell based on information provided by the feature recognition algorithms and systems. 
         [0006]    Specifically, an embodiment of the invention is directed to a method for automatically adding a wax guard to a hearing aid shell impression, comprising; providing a digital 3D representation of a hearing aid shell impression; automatically identifying location information for a canal, tip of the canal, and central line of the impression; determining a first wax guard plane at a predefined flip distance from the canal tip along the central line; determining a second wax guard plane at a predefined canal tip offset distance from the canal tip along the central line; calculating a size and position for a feature of the wax guard based on predefined parameters; and constructing the wax guard utilizing the calculated size and position. 
         [0007]    An embodiment of the invention is directed to a computer-based system for automatically adding a wax guard to a hearing aid shell impression, comprising: a processor; a user display device connected to the processor; a data storage device connected to the processor and the user display device, the storage device containing a 3D representation of a hearing aid shell impression; a software module for automatically identifying location information for a canal, tip of the canal, and central line of the impression from the 3D representation of the hearing aid shell impression; a software module for determining a first wax guard plane at a predefined flip distance from the canal tip along the central line; a software module for determining a second wax guard plane at a predefined canal tip offset distance from the canal tip along the central line; a software module for calculating a size and position for a feature of the wax guard based on predefined parameters; and a software module for producing a finished model of the shell including the wax guard utilizing the calculated size and position. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0008]    The invention is described in detail below with reference to various preferred embodiments as illustrated in the figures and appertaining following description. 
           [0009]      FIG. 1A  is a pictorial drawing of a bell bore implementation; 
           [0010]      FIG. 1B  is a pictorial drawing of a result of the bell bore implementation; 
           [0011]      FIGS. 2A-C  are image files of an open wax guard system; and 
           [0012]      FIG. 3  is an image file illustrating a use of the gluing area option. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]    Multiple designs of the wax guard system are described below, including the bell bore design, the open design, Philip design, and the flip design. With the bell bore design, the wax guard is constructed by software; with the flip wax guard design, the wax guard is drilled inside the shell, and with the open wax guard and the Philip wax guard designs, the wax guard is glued on the canal tip. The following provides a more detailed discussion. 
       Bell Bore Wax Guard Design 
       [0014]      FIGS. 1A through 2C  illustrate the primary parameters that are utilized in the bell bore wax guard system generation. As noted previously, the bell bore is one of the types of wax guards available, and is illustrated in  FIG. 1B . Other types of wax guards are possible, such as one with a completely flat shell tip, like the one shown in  FIG. 1B , but with the mound depth equal to 0. In this case, a real wax guard protection system is drilled inside the shell after the manufacturing of the shell. Another type of wax guard is an open wax guard as illustrated in  FIG. 2C . In this case, a real wax guard protection system is glued on the top of open wax guard. 
         [0015]    Referring back to  FIG. 1A , a shell model/impression  10  is illustrated in having a canal tip  12 . A cutting plane  14  is applied to the canal tip  12  ( FIG. 2A ) at a distance defined by a canal tip offset  28 . The result of applying the cutting plane  14  can be seen in  FIG. 2B . 
         [0016]    A series of parameters in addition to the canal tip offset  28  may then be applied to the shell  10  after application of the cutting plane  14 . These include parameters related to a mound  16 , such as the mound radius  22 , mound distance  24 , and mound depth  34 . Parameters associated with a related bore  18  are also applied to the shell  10 . These include the bore depth  26  (which is the same as the mound depth  34 ), and bore fillet radius  30 . 
         [0017]    According to an embodiment of the system, two principal planes are computed along a z-axis of the shell impression  10 , with the canal tip  12  serving as the reference point for these planes. The canal tip region is automatically identified by the software system. The initial bore depth plane  20  is placed on a centerline along the z-axis at a configurable offset distance from the canal tip  12 , called the flip distance  15 . The centerline is generated along vertical scans of the impression  10 . 
         [0018]    The second cutting plane  14  is placed along the z-axis centerline at a configurable offset distance from the canal tip  12 , called the canal tip offset  28 . A bore depth  26  can then be determined as the difference between the flip distance  15  and the canal tip offset  28 . The mound distance  24  can then be determined based on a configurable percentage (PercentMD) of a major axis of the generally elliptical shape formed by the intersection of the flip distance plane  20  and the outer surface of the canal portion. 
         [0019]    A mound radius  22  can be defined as a configurable percentage (PercentMR) of the mound distance  24 , and a mound bore fillet radius  30  can be defined as a configurable percentage (PercentFIR) of the mound distance  24 . Any of the configurable parameters described herein can be accessible on a display of a user interface device according to known user interface objects, e.g., a preferences tab on a dialog box of the display. A user can adjust the planes  14 ,  20  if required by rotating and translating the planes. However, for translation, a constraint is made so that any translation is constrained to the z-axis, whereas rotation is allowed along the x- and y-axis. This is because planes  20  and  14  are parallel and the X and Y axes are located on the planes with the Z-axis being perpendicular to both planes. Thus, if user were to try to rotate the planes around the Z-axis, the picture will not change at all, because the planes have infinite dimensions in the XY plane. If the user tries to translate the planes in the X or Y axis, the picture will not change here either, because the Z axis still remains perpendicular to the plane, and, as plane is infinite, there is no change in the plane positions. When displaying an image of the impression  10  on the user interface device, the bore area can be presented in a transparent manner when it is selected. 
       Open Wax Guard Design 
       [0020]    The open wax guard system can be presented to the user as an option for operating the system. The open wax guard system can be generated based on the general protocols defined for a bell bore design above by simply setting all parameters except the flip distance  15  to zero. The software then inserts and creates an open wax guard based on the flip distance  15  as defined previously. The default thickness of the open wax guard can be same as the shell wall thickness (see the illustration in  FIGS. 2A-C ). 
       Philip Wax Guard Design 
       [0021]    The Philip wax guard can be implemented similar to the open wax guard design cut, however, a faceplate gluing option “extra gluing area” can be specified for the Philip wax guard in the wax guard option preferences for the user interface. If this option is chosen, the open wax guard is built as shown in  FIG. 2C . Then the open wax guard is modified in a way similar to the way the normal shell is modified but on the tip side and not on the faceplate side, as illustrated in  FIG. 3 .  FIG. 3  illustrates the transition height  40 , the gluing surface width  42 , and the gluing surface thickness  44 . The structure “gluing area” is built on the faceplate side of the shell. In the case of the Philip wax guard the structure is the same, but on the canal side, where open wax guard was applied. It is not necessary to build the gluing area on the faceplate side of the shell for Philip wax guard. 
         [0022]    Under this design option, the receiver hole functionality is disabled for the Philip wax guard option; the receiver hole is a functionality used to drill the hole on the tip of the shell. In the case of the Philip wax guard, the tip is open (like in the open wax guard design), and therefore, there is no place to drill the receiver hole. 
       Flip Wax Guard Design 
       [0023]    The flip wax guard can be implemented similar to bell bore with all parameters except the canal tip offset  28  set to zero. 
       Automatic Wax Guard Positioning 
       [0024]    Similar to the implementation of the bell bore design, feature recognition algorithms are run on the given shell  10  to identify the canal  11 , tip of the shell  12  and the central line  13 —this software automatically recognizes the canal  11  and the tip of the canal  12 , as well as the central line  13  of each impression  10 . The feature recognition algorithms take the undetailed shell as an input and identify different shell features on the shell, such as the tragus, anti-tragus, concha, helix, etc. One of the features that is identified by the feature recognition algorithms is the canal tip  12 ; another feature is the central line  13 . The tip  12  of the shell is the deepest point on the impression when it is inside the human ear, and the central line  13  is a 3D line inside the shell defined by being equally remote from shell surface on every cross-section. 
         [0025]    The software ensures that the canal tip  12  and the central line  13  are detected correctly. Incorrect detection of these features may result in a mis-functioning of the automatic wax guard placement. If feature recognition algorithms fail to detect either the central line  13  or the canal tip  12  or both, an error message should be reported to the user via the user interface, log file, or the like, and the automatic wax guard positioning should be paused or terminated. Further status information about the detection process can be provided to the user to assist in determining the cause of failure. 
         [0026]    The positioning algorithms described herein can interface to a separate feature recognition module via a defined set of interfaces or interface routines. In an optimum system, processing capability is provided to implement the automatic wax guard placement in less than approximately one second in order to facilitate real-time use. 
         [0027]    Once the respective features have been determined, a backend database of the system is read to determine which type of wax guard protection system is requested—these can be in the form of manufacturing option codes. The appropriate algorithms described above can then be implemented. The flip distance  15  is measured from the tip of the canal  12  along the central line  13  towards the aperture. 
         [0028]    The wax guard plane  20  is positioned perpendicularly to the central line  13  at the flip distance  15  from the tip of the canal  12 . The canal tip offset distance  28  is measured from the tip of the canal  12  along the central line  13  towards the aperture. The second wax guard plane  14  is positioned perpendicularly to the central line  13  at the canal tip offset distance  28  from the tip of the canal  12 . After the planes  14 ,  20  are determined, the position and size of bell bore mounds may then be calculated, based on the configurable parameters discussed above, and the bell bore can be built. For the bell bore construction, the membrane is positioned on the plane  14  and glued onto the mound  16 . The whole structure of the bell bore with membrane the wax guard on the finished product. 
         [0029]    For the purposes of promoting an understanding of the principles of the invention, reference has been made to the preferred embodiments illustrated in the drawings, and specific language has been used to describe these embodiments. However, no limitation of the scope of the invention is intended by this specific language, and the invention should be construed to encompass all embodiments that would normally occur to one of ordinary skill in the art. 
         [0030]    The present invention may be described in terms of functional block components and various processing steps. Such functional blocks may be realized by any number of hardware and/or software components configured to perform the specified functions. For example, the present invention may employ various integrated circuit components, e.g., memory elements, processing elements, logic elements, look-up tables, and the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices. Similarly, where the elements of the present invention are implemented using software programming or software elements the invention may be implemented with any programming or scripting language such as C, C++, Java, assembler, or the like, with the various algorithms being implemented with any combination of data structures, objects, processes, routines or other programming elements. Furthermore, the present invention could employ any number of conventional techniques for electronics configuration, signal processing and/or control, data processing and the like. The word mechanism is used broadly and is not limited to mechanical or physical embodiments, but can include software routines in conjunction with processors, etc. 
         [0031]    The particular implementations shown and described herein are illustrative examples of the invention and are not intended to otherwise limit the scope of the invention in any way. For the sake of brevity, conventional electronics, control systems, software development and other functional aspects of the systems (and components of the individual operating components of the systems) may not be described in detail. Furthermore, the connecting lines, or connectors shown in the various figures presented are intended to represent exemplary functional relationships and/or physical or logical couplings between the various elements. It should be noted that many alternative or additional functional relationships, physical connections or logical connections may be present in a practical device. Moreover, no item or component is essential to the practice of the invention unless the element is specifically described as “essential” or “critical”. Numerous modifications and adaptations will be readily apparent to those skilled in this art without departing from the spirit and scope of the present invention. 
       TABLE OF REFERENCE CHARACTERS 
       [0000]    
       
           10  shell model 
           11  canal 
           12  canal tip 
           13  central line 
           14  cutting plane 
           15  flip distance 
           16  mound 
           18  bore 
           20  bore depth plane, flip distance plane, or wax guard plane 
           22  mound radius 
           24  mound distance 
           26  bore depth 
           28  canal tip offset 
           30  bore fillet radius 
           34  mound depth 
           40  transition height of gluing area 
           42  gluing surface width 
           44  gluing surface thickness