Abstract
Aiming at individualized acoustic transparency for users of in-ear hearing systems, we investigate to which extent it is possible to estimate open-ear sound transfer from measurements taken while wearing an in-ear hearing system that is blocking the ear canal. One of the prerequisites for an ideal estimation of the open-ear characteristics is that the sound field within the ear canal be one-dimensional (along a curved axis). This is a valid assumption for low frequencies and positions away from the concha, ear canal bends and the eardrum, but may be questionable at typical earpiece faceplate locations. The main research question concerns the distribution of sound pressure across the surface of the faceplate of the earpiece with and without vent, compared to an open ear canal for different angles of sound incidence. First results of BEM simulations for three individual head geometries of the IHA database indicate that for the frequency range up to about 4 kHz the sound pressure distribution on the faceplate surface is sufficiently even, such that a one-dimensional approach to construct individualized transparency filters appears to be feasible.