Characterizing the perceptual diffusion of auditory lateralization images

Abstract

When two statistically independent noise sources with different interaural time delays are presented simultaneously over headphones, the separated source images seem to become diffuse and merge over time. Experiments were designed to test the hypothesis that the measure of diffusion perceived would increase over time. Target stimuli were created consisting of the two simultaneous sources with different interaural time delays, and attempts were made to study the diffusion as a function of stimulus duration, as well as relative onset of the two noise sources. These target stimuli were compared to a set of partially decorrelated noise stimuli composed of three statistically independent sources. It was hoped that by varying the degree of decorrelation in these comparison stimuli, one could simulate different stages in the transition from two source images to one merged image observed in the target stimuli. The experiments failed to produce the expected results, but strategies for improved experimental designs were devised.