Localization of virtual sound sources synthesized from model HRTFs

Published data from our laboratory and others suggest that under laboratory conditions human listeners localize virtual sound sources with nearly the same accuracy as they do real sources. The virtual sources in these experiments are digitally synthesized and presented to listeners over headphones. Synthesis of a given virtual source is based on freefield to eardrum acoustical transfer functions ("head-related" transfer functions, or HRTFs) that are measured from both ears of each individual listener. It folllows that synthesis of a virtual auditory space of 265 source locations for each listener requires storage and processing of 530 complex, floating-point HRTFs. If each HRTF is represented by 256 complex spectral values, the total database consists of 271,360 floating-point numbers. Thus, while the perceptual data may argue for the viability of 3-dimensional auditory displays based on the virtual source techniques, the massive data storage and management requirements may impose some practical limitations.