A numerical study of multichannel systems for the presentation of virtual acoustic environments

The objective of this thesis is to undertake a numerical study of virtual acoustic imaging systems of which performance may be nearly independent of individual ear shape. The system developed aims to reproduce the incident sound field on the ear using a multichannel headphone. This has been called the RISE (Reproduction of the Incident Sound on the Ear) system in this thesis. The multichannel headphone reproduction uses the boundary surface control principle derived from the Kirchhoff-Helmholtz integral equation. The performance of the system using the incident sound field reproduction method can be made to be independent of the geometry and boundary condition of the scattering body within the control volume. The results of computer simulations show that the desired sound pressure at the eardrum of an arbitrary listener can be successfully replicated in the virtual acoustic environment by using the RISE system. The optimal strengths of headphone sources can be evaluated by using a dummy head model without the ears. This implies that anyone can experience nearly the same quality of the virtual sound field that can be created inside the multichannel headphone of the RISE system. The optimization of the multichannel headphone has been studied in terms of the size of the control volume and headphone, the number of headphone sources, and the boundary condition of the headphone surface. For example, 17 evenly distributed headphone sources per ear can reproduce any angle of incident sound on the ear reasonably well in three-dimensional space up to at least 10kHz. Highly absorbent inner surfaces of the headphone are required.