Fitting an electro-acoustic model of a vented earpiece to 3D fem simulations for the prediction of the ear canal input impedance

International audience; In order to ensure optimal sound presentation by hearing systems, the sound pressure at the eardrum should be controlled. Since the sound pressure at the eardrum varies individually and direct measurements are tedious, it is desirable to be able to predict it individually, which requires knowledge of the involved transfer functions. For an earpiece with multiple receivers and microphones, an electro-acoustic model was developed by [Vogl and Blau, 2019], which was used to determine the impedance of the residual ear canal and subsequently to estimate the individual sound pressure at the eardrum. Recently, an improved prototype of this earpiece, featuring an updated design of the vent and arrangement of microphones and receivers, was developed and made available to the public [Denk et al., 2019]. In this contribution, an electro-acoustic model of the new earpiece is proposed. In addition to modifications of the model structure, the model parameters are now optimized using simulated transfer functions based on a 3D- FEM-model of the earpiece instead of measurements. This avoids measurement inaccuracies, bypasses the uncertainty of microphone sensitivity and source parameters of the receivers, and offers the advantage of being able to derive impedances at any point of the simulated sound field. Results show that the electro-acoustic model can be trained very accurately. This in turn promises more accurate results in the subsequent prediction of the sound pressure at the eardrum. Funded by the Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 352015383 - SFB 1330 A4 and C1.