An Ear Canal Transmission Model Applied to an Ear Simulator and Compared to Finite Element Modelling

Virtual reality audio primarily relies on binaural rendering, which in turn is based on providing specifically processed audio signals to the listener. However, most of the time, these precisely calculated signals are played over headphones under the assumption that the transmission through the ear canal would not significantly modify them. While this is true for low frequencies, it most certainly is not for higher ones, especially when using closed in-ear earphones. Although it is impractical to include the ear canal transmission in a binaural model or measured HRTFs, as it depends on the model and fit of the headphones among other things, modelling it at the time of rendering is possible. The model would have to be specific to the individual as well as the headphones/earphones used, and its parameters would have to be determined using data that can be realistically obtained just before or during a listening session, without invasive and/or complicated procedures. A method to build such a model is proposed, using measurements from sensors that could be built into an earphone. The method is tested on an ear simulator in laboratory conditions using a custom setup. Model results are validated by acoustic measurements and compared to finite element method simulations in COMSOL.