Distance simulation in virtual audio displays

Advances in the field of audio virtual reality have focused on the simulation of direction in virtual audio displays. The potential to add elementary distance cues to these displays remains largely unexploited. A number of audio cues have been identified that provide exocentric, or relative, and egocentric, or absolute, distance information. Two of these cues, intensity and first-order reflections, are examined closely in this paper. These cues can be simulated in a virtual audio display using simple geometric calculations and digital signal processing techniques. A short experiment examining the effectiveness of these cues was performed. Subjects were asked to make absolute distance judgements based on simulated sound sources while listening to loudspeakers directly or binaural recordings. Half of the trials contained intensity cues only and half contained intensity and reflection cues. The results show that the subjects were able to rank the distances correctly in each condition, but the data fail to verify the effectiveness of the reflection cue when presented over headphones