Dynamic Balanced Model Truncation of the Spherical Transfer Function for Use in Structural HRTF Models

The Spherical Transfer Function (STF) has previously been used in structural HRTF modelling as an analytical approximation to the human head. Versions based on both spherical and spheroidal solid bodies have been incorporated into a range of systems, such as the well known Brown & Duda [1] structural model. STF-based models provide a way to simulate frequency dependent head shadowing (ILD) and time delay (ITD) effects, which can form the foundation for structural HRTF representation. We derive and implement a customizable approximation of the STF based on Balanced Model Truncation, and utilize its inherent modular characteristics to synthesize binaural signals from monaural input with relatively low cost implications.