Resolution of front-back confusion in virtual acoustic imaging systems

A geometric model of the scattering of sound by the human head is used to g enerate a model of localization cues based on interaural time delay (ITD). The ITD is calculated in terms of the interaural cross-correlation function (IACC) for sources placed at a series of azimuthal angles in the horizonta l plane. This model is used to simulate the pressures generated at the ears of a listener due to real sources and due to a two-channel and a four-chan nel virtual source imaging system. Results are presented in each case for t he variation of ITD with head rotation. The simulations predict that the ra te of change of the ITD with head rotation produced by a real source and re plicated by the four-channel virtual source imaging system, cannot be repli cated by the two-channel system. These changes to the ITD provide cues whic h allow resolution of front-back confusion. The results of subjective exper iments are also presented for the three cases modeled. These results strong ly support the findings from the modeling work indicating that, for the sys tems described here, front-back confusion is resolved through changes to th e ITD arising from head motion. (C) 2000 Acoustical Society of America. [S0 001-4966(00)03112-X].