Elementary real-time implementation of a virtual acoustic display based on ADVISE

Abstract

A new theory for high definition Virtual Acoustic Display (VAD) based on a model called the “Virtual Sphere (VS) model” is introduced in this paper. This method is named ADVISE (Acoustic Display based on the VIrtual SpherE model). In ADVISE, a sphere-shaped boundary is defined around a listener, and the sound transmission from the sound source in the original field to the entrances of the listener’s ears is divided into two parts. One consists of Head-Related Transfer Functions (HRTFs) corresponding to the points on the boundary of the virtual sphere, and the other consists of Room Transfer Functions (RTFs) from the sound source to the points on the boundary. Then, these two kinds of transfer functions are convolved in real-time, taking into account the dynamic changes in these functions due to the listener’s head movement. The Kirchhoff-Helmholtz boundary integral equation is the theoretical basis of this idea. This equation represents that a sound field generated by sound sources outside a certain closed boundary can be synthesized by phantom monopole and dipole sources distributed on the boundary. In this paper, the theory of ADVISE is stated, then the features of ADVISE are described.