Velocity Judgments of Moving Sounds in Virtual Acoustic Displays

Abstract

A pure tone sound source, moving along a linear left-to-right trajectory, was simulated over headphones. Six attributes of the object motion were varied independently in a randomized block, factorial design experiment. The independent variables included: 1) sound source velocity, 2) distance from the observer, 3) interaural time delays, 4) Doppler frequency shifts, 5) overall intensity and 6) signal duration. Eight listeners estimated the magnitude of the velocity of the simulated moving sound source in miles per hour. Five of the six independent variables were found to make statistically significant (p<.05) contributions to estimates of velocity magnitude. Correct velocity estimates were found to be moderately correlated with the minimal distance between the trajectory path and the observer, Doppler frequency shifts, and intensity changes. The simulated velocity of the sound source and interaural time delay variables, although statistically significant, explained less than ten percent of the variance in the data. Implications of these research findings for virtual acoustic display design are discussed.