Abstract:
A method is provided for automatically determining the position of and placing a faceplate assembly on a hearing instrument shell that takes into account patient anatomical features. These anatomical features of the shell are used as landmarks for ensuring that the final position of the faceplate on the hearing instrument is optimized both in terms of esthetics and increased comfort. The protocols defined herein take advantage of the intrinsic features of the human ear anatomy and the geometry of the electronic components to ensure that design and manufacturing of ITEs are optimized for efficiency and the process can be completely automated to ensure consistence and practice reproducibility.

Description:
BACKGROUND 
     The present invention is directed to a method for automating the placement of a faceplate in a hearing instrument using rule-based protocols based on characteristic shell features and collision detection protocols. 
     The envisioned faceplate placement protocols use impression features obtained from a mold  10  ( FIGS. 1A-1C ) of the ear canal meatus and external ear. Using principal component analysis (PCA) techniques, characteristic features of the impression, such as the tragus  18 , anti-tragus  14 , and anti-helix  26  are clearly demarcated. Furthermore, optimization techniques such as genetic algorithm, stochastic optimization, memetic algorithm, and/or general combinatorial optimization algorithms are also key algorithmic candidates for the determination of impression features within wide demographic population.  FIG. 2A  illustrates definitive landmarks for a datum plane of an impression  10 .  FIGS. 2B and 2C  illustrate corresponding portions of a human ear and impression made therefrom. 
     A typical in-the-ear (ITE) hearing instrument comprises the following key electronic components:
         A microphone that picks up the sound and transfers it to the amplifier;   A receiver that makes the sound louder and helps correct any sound distortion;   A volume control that adjusts loudness;   A battery that supplies the power; and   A push button that toggles between programmed settings.       

     In a traditional hearing aid design, the shelf  10 ′ of the hearing aid undergoes a number of manual and labor-intensive operations in a multi-process procedure. These processes occur in order to reduce a raw impression  10  to a prescribed hearing aid instrument. 
     One stage of this multi-process procedure is the interactive placement of the faceplate. This is initiated virtually in order to a priori determine whether the prescribed device can be built for the given impression. Furthermore, the final position of the faceplate is considered that which is most optimum, anatomically more comfortable, and collision free (meaning that it does not interfere with electronic components or other parts of the shell). 
     All hearing instruments have electronic components, such as batteries, a microphone, a push button(s), a volume control, hybrids, programming contacts, and a faceplate which serves as a carrier for these components. Due to the anatomy of the ear canal, some protruding electronic components, such as the pushbuttons and volume controls, have to be positioned such that they so not come into contact with the patient&#39;s ear. Hence significant effort is undertaken during the design phase of the casing of the hearing instrument to ensure that patient comfort is accounted for. 
     SUMMARY 
     The present invention is directed to ensuring that the placement of the faceplate and its attendant components is automated to ensure efficiency in the design process, adapting to the anatomical complexity of the patient&#39;s ear, and ensuring a collision-free component-shell interaction. 
     Accordingly, in various embodiments of the invention, a method is provided for automatically positioning a faceplate assembly on a hearing instrument shell, comprising: automatically determining at least one anatomical feature of the hearing instrument shell based on a 3-D data representation of the shell; automatically determining a position of the faceplate assembly on an outer surface of the hearing aid shell based on the at least one anatomical feature; ensuring that the position of the faceplate assembly does not cause a collision (collision detection) with the hearing instrument shelf or other hearing aid components; and outputting the position of the faceplate assembly at an output of a computer. 
     To accomplish this, faceplate placement protocols of the five key types of in-the-ear instrument are outlined below. Furthermore, algorithm-based protocols that implement this automation will be highlighted for each hearing instrument type. An automated method for hearing aid faceplate placement is provided that is implemented with a computer and also, at the same time, takes into account the physiological shape of the ear. 
     These may be implemented on a general purpose computer having a processor that executes code contained with software modules for implementing the algorithms. The computer has a memory for holding the software modules during execution and a permanent storage for storing the software modules when the computer is not powered on. The computer has a user interface with an input (e.g., keyboard, mouse), and an output (e.g., display screen). The computer itself comprises a network connection and other forms of inputs and outputs. The software modules can be stored on a computer readable media. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The invention is described in detail below with reference to various preferred embodiments as illustrated in the figures and appertaining following description. 
         FIGS. 1A-C  are pictorial illustrations of the basic impression feature definitions for a faceplate datum plane; 
         FIG. 2A  is a pictorial illustration showing definitive landmarks for a datum plane of an impression; 
         FIGS. 2B  &amp; C are pictorial illustrations showing the parts of the ear and corresponding parts of the hearing aid impression; 
         FIGS. 3A  &amp; B are pictorial drawings illustrating faceplate placement in a hearing aid with a full shell (FS) design; 
         FIGS. 4A  &amp; B are pictorial drawings illustrating faceplate placement in a hearing aid with a half shell (HS), canal (CA), and mini-canal (MC) designs; and 
         FIGS. 5A  &amp; B are pictorial drawings illustrating faceplate placement in a hearing aid with a completely-in-canal (CIC) design. 
         FIG. 6  is a pictorial illustration showing a typical semi-modular integrated shell with an opened battery door; 
         FIG. 7  is a flowchart illustrating shell design protocols including sequential collision verification, constraint identification, and shell size optimization protocols; 
         FIG. 8  is a pictorial illustration showing a hearing instrument impression with a defined datum plane along the tragus, anti-tragus and anti-helix; 
         FIG. 9  is a pictorial illustration of a typical hearing instrument electronic module comprising a trimmers, push button, battery door, and defined datum plane; 
         FIG. 10  is a pictorial illustration of a scanned electronic module showing key orientation mark points; 
         FIG. 11  is a pictorial illustration showing the synchronization of datum planes of the faceplate/electronic and shell impression; 
         FIG. 12  is a pictorial illustration of a typical impression with landmark features of hearing instrument; 
         FIG. 13  is a pictorial illustration of the relative axis location on the faceplate/electronic module; 
         FIG. 14  is a pictorial line drawing illustrating the alignment of datum planes of the faceplate and shell; 
         FIG. 15  is a pictorial illustration of a sliced impression and faceplate/electronics showing an elliptic center of the impression and the centroid of the faceplate/electronics; 
         FIG. 16  is a pictorial illustration of a centerline in a typical ITE hearing aid shell; 
         FIG. 17  is a pictorial illustration showing the reference helix contour/plane; 
         FIG. 18  is a flow chart of a method carried out in accordance with the present invention; and 
         FIG. 19  is a block diagram of a system (simplified) operable in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     According to various embodiments of the invention discussed below, the placement and integration of the faceplate is automatically performed. Computer software running on a general purpose computer simulates the faceplate placement and ensures that the final position of the faceplate results in the optimal collision free position. Accordingly, the software ensures that the final orientation is based on defined rules for a particular shell type. 
       FIGS. 3A-5B  illustrate anatomically aware faceplate orientation and placement during the design of a custom hearing instrument according to different shell  10 ′ types.  FIGS. 3A and 38  illustrate a full shell (FS) design  10 . 1 ′.  FIGS. 4A and 4B  illustrate half shelf (HS), canal (CA), and mini-canal (MC) designs  10 . 2 ′. Finally,  FIGS. 5A and 58  illustrate a completely-in-canal (CIC) design  10 . 3 ′. Each of the figures illustrate the location of various features of the hearing aid shell  10 ′. Accordingly, the features of the helix  12 , anti-tragus  14 , vent  16 , tragus  18 , microphone  20 , crus  22  and concha bowl  24  can be seen. A faceplate and attendant electronic controls orientation implemented according to these embodiments of the invention ensure a comfortable and optimum control. 
     Battery Door Placement 
       FIG. 6  illustrates a typical semi-modular integrated shell  10 ′ with an opened battery door  52  having a battery  50  in a battery compartment  54 . 
     For an in-the-ear (ITE) device  10 . 1 ′, the battery door  52 , which forms part of the electronic module, is positioned such that it opens away from the tragus  18 . But for HS, CA and MC designs  10 . 2 ′, the battery door  52  is positioned such that it opens towards the tragus  18 . In the CIC design  10 . 3 ′, the battery door  52  is positioned so that it opens away from the vent hole  16 . For each of these device types, the determination of the aforementioned landmarks is key to ensuring that the faceplate  30  is anatomically well-positioned. 
     Collision Detection 
     The software is designed to ensure that collision detection is facilitated between merge surfaces and the components of the hearing aid. An overall flowchart  100  showing the context of the collision detection can be seen in  FIG. 7 . What is significant here is that such automated placement protocols for hearing instrument faceplate placement is implemented in a 3-dimensional modeling software system. 
     3D data representing the shell is loaded  104  from a database  102 . The system can receive a file formatted as a Standard Tessellation Language (STL) or 3D-point cloud as input from any of commercially available 3-D scanner systems, such as, Cyberware, Minolta and iSCAN, or in other decodable proprietary and non-proprietary 3D readable format. Furthermore, the corresponding faceplate geometry can be provided in STL format as well. 
     Vertices of intersecting triangles on the faceplate  30  and the merge surfaces on the shell  10 ′ are computed algorithmically  106 . Various elements are applied to the design such as the shell wall thickness  108 , the vent  110 , receiver hole  112 , and receiver  114 . 
     At this point, a collision check  116  is performed. An algorithm may utilize a “collision responses”, which simply may be likened to a repulsive force that avoids continuous collision between intersecting triangles. Such algorithms include close relative distance computation algorithms where intersecting triangles are repulsed. Additionally, traditional collision detection protocols, which return a true/false Boolean value as an indication of a geometric interaction of triangles may be utilized for this. 
     In geometric programming, collision detection algorithms are classified into two distinct groups: a) feature based algorithms, and b) hierarchical bounding volume algorithms. This classification of collision detection protocols is based solely on the distinct advantages and drawbacks associated with each protocol. In hearing instrument design, a collision is checked during component placement to ensure that the device size is optimized and the placement of the components do not impact the anatomical structure of the ear impression. 
     Feature based algorithms, in general, are better suited for exploiting temporal coherence in the model. In feature based algorithms, infinitesimal motions of the simulated objects require minimal correction to determine the new closest feature pairs. Furthermore, in feature based collision protocols, the object is generally segmented into points, line segments and facets. Such segmentation ensures that each of these discrete entities can be tagged and monitored with the simulation protocols. 
     Hierarchical bounding volume algorithms require miniscule underlying geometric models of the simulating object(s). In general, non-convex objects, polygon soups, are easily handled by hierarchical bounding volume approaches. 
     In addition to the standard collision protocols, these protocols can implement a configurable penetration index. This index determines: 
     1. Which electronic components are allowed to interact freely without evoking collision; and 
     2. What penetration depth is allowed between the meshed surfaces of the electronic components before collision detection is triggered. 
     In the collision check step  116 , if a collision is detected, the steps associated with applying the shell wall thickness  108 , vent  110 , receiver hole  112 , and receiver  114  are performed again, and the check  116  is repeated. 
     If there is no collision up to this point, then positioning of the electronics faceplate  118  is performed, and a subsequent collision check  120  follows. If a collision is detected at this point, then the software repeats the preceding steps from the point of applying the vent  110 - 120 . 
     Note that the vent and receiver are optimizable parameters that exist within the art today. The resolution of these constraints is not the focus here, and any algorithm developed to optimize the faceplate process has to be adaptive enough to resolve these constraints. 
     If there is no collision, then a verification may be performed via a user interface  122 . The user can manipulate the STL file using an input device such as a mouse, joy stick, spaceball, or the like. In a preferred embodiment, the initial placement of the faceplate is automatically implemented using feature recognition and the device based rule-based protocols. However, although  FIG. 7  and the above description shows a utilization of the user interface  122  after the later collision check  120 , the user interface  122  can clearly be utilized at any stage during the process for either verification or control purposes. 
     The implemented collision feedback mechanism can provide a visual indicator on the user interface  122  when a collision is present. For example, a collision between the faceplate  30  and electronic components with shell  10 ′ might be displayed in a configurable color that differs from that used for the faceplate  30 , other components, and shell  10 ′. The color display can be automatically highlighted by the system to show the user where the interaction between the components occur. Of course, any visual indicia, such as shading or other visual attribute, such as flashing, etc. may be utilized. 
     As illustrated in  FIG. 7 , when a design has been completed with no collisions amongst the elements, the design may be stored  124  in the database  102 . 
     Human Interactive Protocols 
     In the interactive implementation, the user can be provided with a way to select corresponding features on the impression  10  and on the faceplate/electronic module  30 . Using the selected landmarks as inputs, the software can then align the faceplate/electronic module  30  with the impression  10 . Furthermore, the software can further provide the user with the ability to store the coordinates of the landmark data in the database  102 . This stored information can serve as a basis for comparative analysis of the system landmark computations against human assisted data acquisition. 
     Computer-Aided Automated Protocols 
     In the automated protocols, the software can use definitive features acquired in real time from the specific impression  10 . This can be accomplished using techniques, hardware, formulae, and procedures described in U.S. patent application Ser. No. 11/612,616, entitled “Intelligent Modeling Method and System for Earmold Shell and Hearing Aid Design”, issued as U.S. Pat. No. 7,605,812 on Oct. 20, 2009, herein incorporated by reference. The system can then define the corresponding datum planes along the faceplate/module  30 .  FIGS. 3A-5B  illustrate a comprehensive overview of the anatomically-aware faceplate placement on the hearing aid instrument for different hearing aid designs. 
     Automatic Faceplate Placement Protocols for In-The-Ear (ITE) Hearing Instruments 
     To facilitate optimum and automated faceplate  30  placement on the hollowed end of the shell  10 ′, the following protocols may be implemented in a three-dimensional geometric-based software system. The protocols under this heading relate to ITE hearing instruments. This software system should have the capability to execute the following protocols, at least in some combination: 
     a) defining a relative coordinate system with origin at the centroid or center of mass of the faceplate/electronics module  30 ; 
     b) generating a shell datum plane  32  ( FIG. 8 ) along a hollowed end  28  ( FIG. 1B ) of the impression  10  using the focal points of the tragus  18 , anti-helix  26 , and anti-tragus  14  as reference points for planar definition. 
     c) generating a corresponding horizontal faceplate assembly datum plane  32 ′ on the faceplate/electronics module  30  as shown in  FIG. 9  with the center of the faceplate assembly datum plane  32 ′ at the centroid or center of mass of the faceplate/electronic module  30  assembly. The horizontal faceplate assembly datum plane  32 ′ should be defined along a contour slice  33  ( FIG. 10 ) of the electronic module  30  whose center coincides with the centroid of the faceplate/electronic module  30  assembly. The contour slices  33  are defined by planes that are generally perpendicular to a vector that perpendicularly intersects the bottom of the tragus  18  trough. In order to determine the faceplate assembly datum plane  32 ′, using PCA, the variation of the parametric contour sizes is monitored. The first largest contour encountered serves as the basis for the definition of the faceplate/electronic datum plane. In other words, contour areas for contour slices  33  for the faceplate/electronic module  30  are determined at predefined intervals 1, 2, . . . N in an X-axis direction towards the trough of the tragus  18 . When a slice  33  is detected having a smaller area than its predecessor slice  33 , then the predecessor slice  33  is determined to be the first largest contour encountered; 
     d) automatically aligning the faceplate assembly datum planes  32 ′ of the electronic/faceplate  30  and the shell datum plane  32  of the impression  10  shown in  FIG. 11 ; 
     e) ensuring that the X-axis of the faceplate/electronic module  30  is directed at the trough of the tragus  18 ; 
     f) ensuring that the geometric centerline  35  of the portion of the shell  10 ′ below the aperture  27  and opening out to the external meatus of the impression coincides with the geometric centroid of the faceplate/electronic module  30 ; and 
     g) ensuring that the electronic faceplate module  30  is collision free and furthermore that the battery  50  does not collide with the concha peak  21  as shown in  FIG. 12 . 
     As illustrated in  FIG. 15 , the centerline  35  is not important in the alignment protocols since the center of the plane generated along the anti-helix, tragus and anti-tragus provides the coincident point required to align the centroid of the faceplate/electronics. 
     Automatic Faceplate Placement Protocols for Canal (C), Half-Shell (HS), and Mini-Canal (MC) Hearing Instruments 
     For the canal (C), half-shell (HS), and mini-canal (MC) hearing instruments, the steps (a)-(g) described above can be implemented with the following exceptions: 
     a) the centerline  35  of the shell  10 ′ can be computed without the helix  12  portion. The centerline  35  is illustrated in  FIG. 16 . This section may be eliminated by a cutting plane inserted along the crus  22  of the impression  10  as illustrated in  FIG. 12  and  FIG. 17 ;  FIG. 17  shows an impression  10  with the helix removed. The computation of the centerline  35  is done as par of the total feature computation of undetailed impression using the same feature set as that of the ITE. In the case of CA, HS and MC when the helix is removed, the centerline is recomputed based on the slicing methodology shown in  FIG. 16 . Thus, the centerline for these shell types intersects the original anti-tragus, tragus and anti-helix plane defined for the undetailed impression. An elliptic center, which is generally the intersection of the centerline and the based plane (anti-tragus, tragus and anti-helix plane) may be slightly shifted from the elliptic center of the ITE. 
     b) the final position of the faceplate/electronic module  30  is rotated 180° along the Z-axis of the faceplate/electronic module  30  ( FIG. 13 ); and 
     c) the system ensures that the crus plane defined between the valley of concha and the helix ridge ( FIG. 17 ) does not collide with the faceplate geometry by providing a configurable minimum distance of separation, 
     Automatic Faceplate Placement Protocols for Completely-In-The-Canal (CIC) Hearing Instrument 
     For the completely-in-canal (CIC) design, the following procedure may be used: 
     a) slicing the shell vertically using standard Principal Component Analysis (PCA) protocols (see Alexander Zouhar, Tong Fang, Gozde Unal, Hui Xie, Greg Slabaugh and Fred McBagonluri, Anatomically-aware, Automatic, and Fast Registration of 3D Ear Impression Models, Third International Symposium on 3D Data Processing, Visualization and Transmission, University of North Carolina, Chapel Hill, USA, Jun. 14-16, 2006, herein incorporated by reference). 
     b) extracting the largest contour at the hollowed end of the shell impression  10 . In the case of a CIC device, this largest contour is the same as the aperture contour of the impression; 
     c) computing the centerline  35  of the canal  25 , which should intersect the aperture  27  plane at the elliptic center of the impression  10  (this is the same as coordinates at the intersection of the major and minor axes of the aperture  27  contour); 
     d) computing the major and minor axes of the aperture  27  contour. This is required because the final position of the faceplate/electronic module  30  is along the major axis of the impression  10 . 
     e) computing the corresponding major and minor axes of the faceplate  30  geometry, as shown in  FIG. 14 ; This is computed along the centroid of the faceplate 
     f) aligning the centroid of the faceplate/electronic module  30  with the elliptic center of the aperture  27  contour. Note that the centerline  35  is a key attribute of this computation alignment of the faceplate/electronic module  30  to the impression  10 . It is updated during a transition from one device type to the other for the same impression. This computation allows the elliptic center to be adapted for each device type. 
     Note that the elliptic center of the impression and the centroid of the faceplate has to be computed as an initial alignment point. Subsequently, as in the case of the CIC the final position of the faceplate/electronics module  30  is along the longest axis of the aperture  27 , which is the major axis. The longest axis of the faceplate/electronics module  30  must be aligned along the major axis of the aperture  27  contour. This may require a final rotation about the elliptic center of the impression  10  which is the principal pivot for the final alignment. 
       FIG. 18  shows a flowchart summarizing a method  150  for automatically positioning a faceplate assembly on a hearing instrument carried out in accordance with the present invention as described above. The method  150  provides automatically determining at least one anatomical feature of the hearing instrument shell based on a 3-D data representation of the shell (Step  152 ) and automatically determining a position of the faceplate assembly on an outer surface of the hearing aid shell based on the at least one anatomical feature (Step  154 ). The method  150  also provides ensuring that the position of the faceplate assembly does not cause a collision (i.e., performs collision detection) with the hearing instrument shell or other hearing aid components (Step  156 ). The method  150  further provides outputting the position of the faceplate assembly at an output of a computer (Step  158 ). 
       FIG. 19  is a block diagram of a computer system  180  (simplified) operable in accordance with the present invention for implementing the above method. The computer system  180 , or general purpose computer, has a processor  182  and a user interface with an input  184  (e.g., keyboard, mouse), and an output  186  (e.g., display screen, network connection to other devices, such as production systems). The processor  182  executes computer-readable coded instructions contained within software modules for implementing algorithms to carry out the method  150 . The system  180  also has a memory  188  for holding the software modules for execution and a permanent storage for storing the software modules when the system  180  is not powered on. The computer system  180  also comprises a network connection and other forms of inputs and outputs. The software modules, and the computer algorithms therein, can be stored on a computer readable media. 
     In the above described manner, the correct faceplate placement can ensue for a wide variety of hearing aid shapes in an automated manner. 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. 
     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. 
     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 
     
         
           10  mold/impression 
           10 ′ hearing aid shell based on mold/impression 
           10 . 1 ′ shell for full shell design 
           10 . 2 ′ shell for half shell design 
           10 . 3 ′ shell for CIC shell design 
           12  helix 
           14  anti-tragus 
           16  vent 
           18  tragus 
           20  microphone 
           21  concha peak 
           22  crus 
           23  cymba 
           24  concha bowl 
           25  canal 
           26  anti-helix 
           27  aperture 
           28  hollowed end of impression 
           29  canal tip 
           30  faceplate/electronics module 
           30 ′ faceplate orientation 
           32  datum plan along tragus, anti-tragus, and anti-helix 
           32 ′ corresponding horizontal datum plane on the faceplatel electronic module 
           33  contour slice 
           35  centerline 
           37  helix removal plane 
           50  battery 
           52  battery door 
           54  battery compartment 
           100 - 124  collision determination flow chart and steps 
           150 - 158  a method of the present invention flow chart and steps 
           180 - 188  computer system for implementing the method of the present invention