Speaker
Description
Accurate binaural rendering of nearby sound sources is key for perceptual plausibility and reliable distance cues in virtual acoustics environments. Achieving this requires modeling of near-field effects, which exhibit a complex dependence on source distance and incidence angle. These effects can be introduced into measured or simulated far-field head-related transfer functions (HRTFs) by applying a near-field transfer function (NFTF). The NFTF may be defined as the ratio of the near-field to the far-field transfer function for rigid sphere scattering as a first approximation for the human head. However, efficient computation of the NFTF remains challenging in interactive virtual acoustics scenes. In this work, we propose a physics-based, low-order filter model for the NFTF comprising two first-order shelving filters. The model directly integrates analytical derivations for the asymptotic low-frequency and high-frequency filter gains based on rigid sphere scattering, while the filters' cutoff frequencies are parameterized by source distance and incidence angle. Because the proposed model is grounded in the underlying physics of rigid sphere scattering with arbitrary radius and distances of source and receiver, it is suited for extensions to broader applications, such as modeling the directional characteristics of sources and the scattering of objects. Objective evaluation demonstrates that the filter model provides an accurate representation for the NFTF with an average root-mean-square error (RMSE) of 0.1 dB and a maximum RMSE of 0.6 dB. These results indicate that the proposed model offers a practical and precise solution for incorporating near-field effects in interactive binaural rendering.