R. H. Gilkey
Armstrong Lab., AL/CFBA, Wright-Patterson AFB, Dayton, OH 45433-6573 and Dept. of Psychol., Wright State Univ., Dayton, OH 45435
Michael D. Good
Wright State Univ., Dayton, OH 45435
The design of three-dimensional auditory displays for virtual environments should consider the potential for interference among sound sources. In the present study, free-field masking was measured between sound sources that were separated in azimuth or in elevation. The click train signal and noise masker were filtered to lie within low- (below 1.5 kHz), middle- (1.2--7.0 kHz), or high- (above 3.5 kHz) frequency regions. As expected, based on headphone data and on traditional models of binaural masking, there was a dramatic decrease in masking (as much as 18 kB) when the sound sources were separated within the horizontal plane. Similar decreases in masking (as much as 9 dB) were observed for the high-frequency signal and masker when they were separated within the median plane. Although phenomenologically similar, the masking release observed in the horizontal plane is likely to depend on interaural cues, whereas, these cues should play a minimal role within the median plane. Differences across frequency regions and differences between continuous and pulsed masker presentation are also discussed. [Work supported by AFOSR-91-0289.]