Claus Nielsen

Research Audiologist

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Completely-In-the-Canal (CIC) hearing-aids have several attractive assets, but they are difficult to produce due to limitations in physical space. Therefore, a 3D model of the ear canal and of the variation across the population is highly desirable.

Starting with proof-of-concept

A statistical 3D shape model of the ear canal was created from a small set of scanned ear impressions. Despite the small set size, it was possible to build an anatomically plausible model. This model was able to explain the major variation in the original data, by combining no more than seven ‘proto-shapes’.


Applications in mechanical design of hearing aids

The shape model was used to develop a software tool to automatically position the faceplate-cut in the production of CIC hearing aids. It was shown that the software could be ‘trained’ to mimic the skills of the best manual operators. In a subsequent stage, a framework was established that could take into account the physical components requiring fitting into the CIC shell, such as microphone, receiver (loudspeaker), battery, and amplifier package.

Further reading

Paulsen RR (2004). Statistical Shape Analysis of the Human Ear Canal with Application to In-the-Ear Hearing Aid Design. Informatics & Mathematical Modelling, Technical University of Denmark, Building 321, Richard Petersens Plads, DK-2800 Kgs. Lyngby.