@CONFERENCE\{IMM2004-02376,
    author       = "R. R. Paulsen and C. Nielsen and S. Laugesen and R. Larsen",
    title        = "Using a Shape Model in the Design of Hearing Aids",
    year         = "2004",
    month        = "feb",
    keywords     = "Human Ear Canal Anatomy, Hearing Aid Design, {3D} Active Shape Model, Iterative Closest Points, Faceplate Placement",
    booktitle    = "{SPIE} - Medical Imaging (to appear)",
    volume       = "",
    series       = "The International Society for Optical Engineering - Medical Imaging",
    editor       = "",
    publisher    = "",
    organization = "",
    address      = "",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/2376-full.html",
    abstract     = "Today the design of custom completely-in-the-canal hearing aids is a
manual process and therefore there is a variation in the quality of
the finished hearing aids. Especially the placement of the so-called
faceplate on the hearing aid strongly influences the size and shape of
the hearing aid. Since the future hearing aid production will be less
manual there is a need for algorithms that mimic the craftsmanship of
skilled operators. In this paper it is described how a statistical
shape model of the ear canal can be used to predict the placement of
the faceplate on a hearing aid made for a given ear canal. The shape
model is a point distribution model built using a training set of
shapes with manually placed landmarks. An interpolation method is used
to generate dense landmark correspondence over the training set prior
to building the shape model. Faceplates have also been placed on the
training shapes by a skilled operator. These faceplate planes are
aligned to the average shape from the shape model and an average
faceplate plane is calculated. Given a surface representation of a new
ear canal, the shape model is fitted using a combination of the
iterative closest point algorithm and the active shape model approach.
The average faceplate from the training set can now be placed on the
new ear canal using the position of the fitted shape model. A
leave-one-out study shows that the algorithm is able to produce
results comparable to a human operator."
}