Numerical calculation method of binaural signals suitable for auralization of a reflective sound field

Abstract

Based on the Kirchhoff‐Helmholtz integral equation, a numerical calculation method, which enables a wave‐theory‐based auralization of a sound field inside room, is proposed. Binaural signals are synthesized from pressures and particle velocities on the boundary surface and corresponding head‐related transfer functions (HRTF). The proposed method can shorten the extra computation time that is required because of changes in numerical conditions caused by head movement and rotation. The boundary element method (BEM) was used to calculate surface values on sound‐reflective objects. In addition, HRTFs for various source positions were calculated using a BEM‐based HRTF calculation system [M. Otani and S. Ise, J. Acoust. Soc. Am. 119, 2589–2598 (2006)]. Results obtained using the proposed method are compared with those of the conventional BEM, whose boundary consists of a head and a wall, and an image source method, which does not incorporate sound wave motion. Those comparisons reveal that the proposed method can accurately simulate binaural signals, including indirect sound from reflective objects. In addition, interactions between the head and wall are discussed, which are omitted in any auralization method using HRTFs to synthesize binaural signals and have not been investigated.