Evanescent Waves at the Interface Between Ear Canal and Otoacoustic Emission Probe

M. Zebian[1,2], J. Hensel [2], and T. Fedtke[2]
[1]Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
[2]International Graduate School of Metrology, Braunschweig, Germany
Published in 2011

Otoacoustic emission (OAE) tests provide an objective examination of the cochlear function. However, the validity of OAE tests is affected negatively by calibration errors. This report sheds light on the evanescent waves arising at the interface between the OAE probe and the ear canal, and analyses the impact of minor eartip modifications on the acoustic length estimation of ear canals, using finite element simulations.

Whereas no tube extensions were considered necessary for an 8 mm-diameter ear canal model, extending the microphone tube by 2 mm led to an improved length estimation of the 12 mm-diameter ear canal model. We expect that modifying the 12 mm-diameter eartips will have a positive effect on the acoustic length estimation of large-diameter ear canals.