Characterizing the outer ear transfer function in dependence of interindividual differences of outer ear geometry
The outer ear transfer function can be used to describe the influence of the outer ear canal and its geometric variance in cross-section as well as its path on the sound field in the ear canal and the sound pressure level resulting at the ear drum. The variance of outer ear geometry is described by analysis of polysiloxane castings of the outer ear. Algorithms are developed to determine various parameters of the outer ear geometry and to gain access on a huge amount of data (over 100.000 data sets). Sound transmission in form of the outer ear transfer function is analyzed for various outer ear geometries using a finite element model as well as an experimental setup. In both cases sound (frequency band: 20 Hz to 20 kHz) is send to a model of the outer ear as a plane wave parallel to the plane of the Pinna.