RE: Modeling the Aural canal and 3D scanning

From: Ping Fu (
Date: Fri Mar 08 2002 - 21:29:38 EET

There are 8000 hearing aid dispensers throughput the united states,
many can make a ear impression for you for a fee.
You can search internet or go to to find
a dispenser near you.

Once you have the impression, you can call a service company
to scan, design and make SLA or SLS models for you.

There are three scanning vendors who have dedicated scanning system
for ear impressions, Minolta, LDI and Genex Technology. These scanners
are automatic and ease to user. They take about a minute to scan
the entire impression. There is no scanner can scan ear canal directly that
is commercially available.

Raindrop Geomagic has a software call Geomagic eShell, which
is specifically designed to handle scan data and produce digital
shell for use with Rapid Prototyping machines.

3D systems has both SLA/SLS processes optimized for hearing shell
production. The material is bio-compatible.

The technology in direct production of ear mold is advanced to a
point where turn-key solution is available.

  -----Original Message-----
  From: []On Behalf
Of Bill Richards
  Sent: Friday, March 08, 2002 1:13 PM
  Subject: Modeling the Aural canal and 3D scanning

  I must agree with Dr. Bibb: Never stick anything in your ear (except your

  Hearing specialists routinely make castings of a patient's ear canal with
a soft material in order to create a custom fit hearing aid. Please go to
your doctor to find out where you can have this done safely. I can't imagine
that anyone would find having their eardrum ripped out of their body to be a
pleasant experience...

  3D scanning technology is not up to the level that many people would like
to believe. I would put scanning technology at least several years behind
rapid prototyping.

  Laser scanners can only scan what can be seen on a straight line. Over
hangs and folds will never be scanned. Metals, transparent materials, and
materials with translucence or specularity will cause problems with the
scanner determining just where the light beam actually touched the surface.

  Mechanical arm scanners can overcome that issue, so long as the probe can
be worked into the tight places. But the quality of your data depends on the
number of times you touch your probe to the target surface.

  Another type of scanner actually destroys the subject, by shaving it away
layer by layer and imaging each layer. This technique guarantees that hidden
geometries will be scanned. The only other way would be to use MRI or CAT

  For creating a model of an ear, I don't believe you are going to get a
true scan without using MRI or creating some custom probe-scanner. Perhaps
an endoscope with a laser scanning from its tip. I think the best way is as
Dr. Bibb suggested: Have a doctor create a casting of your subject's ear,
and then scan the casting.

  Bill Richards
  Delta Search Labs
  T: 617-551-4615
  F: 617-551-4651

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